Inherit diesease

THE INTRODUCTION TO INHERIT DISEASES
Submitted By: Tasneem Ahmed
Tasneemkhokhar1280/1281@gmail.com

Contents
THE INTRODUCATION TO INHERIT DISEASES.................................................................1
INHERIT DISEASES................................................................................................................. 4
Cell;............................................................................................................................................ 4
Tissue..........................................................................................................................................4
Cell Cycle....................................................................................................................................4
Metabolism.................................................................................................................................4
Mutation.....................................................................................................................................5
DNA And RNA........................................................................................................................... 5
GENES AND ALLELE............................................................................................................... 5
Terminology ............................................................................................................................... 5
Disease........................................................................................................................................6
Genetic disease............................................................................................................................ 7
Hereditary or inherited disease...................................................................................................7
Human Genetics ......................................................................................................................... 7
Genetic Code............................................................................................................................... 8
Genes..........................................................................................................................................8
Genome.......................................................................................................................................8
Chromosomes ............................................................................................................................. 8
CHROMATINMATERIA .........................................................................................................9
Sex chromosomes........................................................................................................................ 9
Mitosis...................................................................................................................................... 10
Meiosis...................................................................................................................................... 10
GENETICS AND GENES........................................................................................................ 11
Inherit Diseases or Genetic Disease........................................................................................... 11
Modes of Inheritance ................................................................................................................ 12
Genetic Disorders ..................................................................................................................... 12
Autosomal Dominant Diseases.................................................................................................. 13
Achondroplasia......................................................................................................................... 15
Hereditary Hemochromatosis................................................................................................... 15
Down Syndrome ....................................................................................................................... 15
Autosomal Recessive Diseases................................................................................................... 15
Polycystic Kidney Disease......................................................................................................... 16
Usher Syndrome ....................................................................................................................... 16
Hereditary Fructose Intolerance............................................................................................... 17
Cystic fibrosis ........................................................................................................................... 17

Gender Linked Diseases............................................................................................................ 17
Color Blindness......................................................................................................................... 17
Hemophilia ............................................................................................................................... 18
Muscular Dystrophy................................................................................................................. 19
Polygenic Disorders .................................................................................................................. 19
Cri Du Chat Syndrome ............................................................................................................. 20
Nondisjunction Genetic Disorders ............................................................................................ 20
Trisomy 21 / Down Syndrome................................................................................................... 21
Trisomy 13 – Patau syndrome................................................................................................... 21
Trisomy 18- Edwards syndrome ............................................................................................... 21
Sex linked Nondisjunction Genetic Disorders ........................................................................... 22
Turner syndrome...................................................................................................................... 22
Klinefeltersyndrome ................................................................................................................ 23
Fragile X Syndrome.................................................................................................................. 24
Chromosomal aberrations (cytogenetic disorders).................................................................... 24
Structural abnormalities........................................................................................................... 25
Clinical symptoms..................................................................................................................... 25
Sex chromosomal disorders ...................................................................................................... 25
Classification of genetic diseases............................................................................................... 26
2. Monogenic (mendelian) disorders ......................................................................................... 27
OTHER INHERIT DISEASES................................................................................................. 27
Thalassemia.............................................................................................................................. 27
Cystic Fibrosis .......................................................................................................................... 28
Sickle-Cell Disease.................................................................................................................... 28
Hemophilia ............................................................................................................................... 28
Huntington’s Disease ................................................................................................................ 29
Down Syndrome ....................................................................................................................... 29
The most common conditions that tend to run in families:........................................................ 29
Solution..................................................................................................................................... 30
Conclusion................................................................................................................................. 31
References................................................................................................................................. 32

INHERIT DISEASES
Cell;All living organisms are composed of one or more cell. The cell is the structural and
functional unit of living organisms.
 The body of unicellular (Prokaryote) organisms are made up of a single cell
 The body of multicellular (Eukaryote) organism is composed of many cells
Tissue;Tissue is a group of cells which perform a common function. All cells of the tissues
are dependent on each other. There is a different type of tissues;
 Connective Tissues,
 Muscular Tissues,
 Nervous Tissues,
 Epithelial Tissues.
Cell Cycle
In living organisms, many processes like growth, reproduction, repairing and healing are
dependent on cell division. The cell cycle consists of 2 main stages:
 Interphase or resting stage; The longest part of the cell cycle is the interphase stage
it is the period between the end of one cell division and the start of next division. In
interphase, the nucleolus and the nuclear envelope are distinct, and the chromosomes
are in the form of threadlike chromatin.
 Division phase (Mitosis or Meiosis; During the division phase, the cell undergoes
division either by Mitosis or Meiosis
Metabolism
The sum of all chemical reactions going on within a living an organism is called
Metabolism. Metabolism consists of anabolism and catabolism.
 Anabolism; is building up; of larger molecules from smaller ones.
 Photosynthesis (CO2+H2O------Glucose)
 Catabolism; is the breakdown of larger molecules into smaller ones
 Respiration (Glucose-----CO2+H2O).COM

Mutation
Mutations are changes in genes taking place while a gene is being replicated. If
a single base pair is not present in the correct order it may alter the characteristics of the
whole gene. It results in the production of another form of that gene. A mutation is a change
that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the
result of environmental factors such as UV light and cigarette smoke
DNA And RNA
DNA stands for deoxyribonucleic acid. It’s the genetic code that determines all the
characteristics of a living thing. Basically, your DNA is what makes you, you! You got your
DNA from your parents, we call it ‘hereditary material’ (information that is passed on to the
next generation). Nobody else in the world will have DNA the same as you DNA & RNA.
GENES AND ALLELE
A gene is the fundamental physical and functional unit of heredity. A gene is an
individual element of an organism’s genome and determines a trait or characteristic by
regulating biochemical structure or metabolic process. Genes are segments of nucleic
acid, consisting of a specific sequence and number of the nucleotides in a linear fashion
that has code for protein synthesis. Characteristics are inherited from parents to offspring.
The locant of the gene on chromosomes is called its Locus. The variation between the
same gene is called alleles and the term used to describe alternate forms of the same gene
is called ALLELIC VARIATION. Alleles occur when there is a difference in the DNA
sequence between pairs of genes
Terminology
In many cases, terms such as disease, disorder, morbidity, sickness, and illness are used
interchangeably. There are situations, however, when specific terms are considered
preferable.
 Genotype- the alleles a person has
 Phenotype- the observable trait a person has

 Dominant- Alleles affect masks the other allele it is paired with
 Recessive- Alleles affect is masked by the other allele it is paired with.
 Homozygous- Pair of alleles for a trait are identical
 Heterozygous- Pair of alleles for a trait are not identical
 Hybrid- Inherit non-identical alleles for a trait
Disease
An abnormal condition of an organism which interrupts the normal bodily functions
that often leads to a feeling of pain and weakness, and usually associated with
symptoms and signs
 an illness that affects a person, animal, or plant
 a condition that prevents the body or mind from working normally
 a problem that a person, group, organization, or society has and cannot stop.
A disease is an abnormal condition that negatively affects the structure or function of a part or
all an organism, and that is not due to any external injury the term disease broadly refers to any
condition that impairs the normal functioning of the body. For this reason, diseases are
associated with dysfunction of the body's normal homeostatic processes. Diseases are often
construed as medical conditions that are associated with specific symptoms and signs. A
disease may be caused by external factors such as pathogens or by internal dysfunctions. For
example, internal dysfunctions of the immune system can produce a variety of different
diseases, including various forms of immunodeficiency, hypersensitivity, allergies and
autoimmune disorders. In humans, the disease is often used more broadly to refer to any
condition that causes pain, dysfunction, distress, social problems, or death to the person
afflicted, or similar problems for those in contact with the person. In this broader sense, it
sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms,
deviant behaviors, and atypical variations of structure and function, while in other contexts and
for other purposes these may be considered distinguishable categories. Diseases can affect
people not only physically, but also mentally, as contracting and living with a disease can alter

the affected person's perspective on life. Death due to disease is called death by natural causes.
There are four main types of disease: infectious diseases, deficiency diseases, hereditary
diseases (including both genetic diseases and non-genetic hereditary diseases), and
physiological diseases. Diseases can also be classified in other ways, such as communicable
versus non-communicable diseases. The deadliest diseases in humans are coronary artery
disease (blood flow obstruction), followed by cerebrovascular disease and lower respiratory
infections. In developed countries, the diseases that cause the most sickness overall are
neuropsychiatric conditions, such as depression and anxiety. The study of disease is called
pathology, which includes the study of etiology, or cause. Commonly, the term is used to refer
specifically to infectious diseases, which are clinically evident diseases that result from the
presence of pathogenic microbial agents, including viruses, bacteria, fungi, protozoa,
multicellular organisms, and aberrant proteins known as prions. An infection or colonization
that does not and will not produce clinically evident impairment of normal functioning, such
as the presence of the normal bacteria and yeasts in the gut, or of a passenger virus, is not
considered a disease. By contrast, an infection that is asymptomatic during its incubation
period, but expected to produce symptoms later, is usually considered a disease. Non-infectious
diseases are all other diseases, including most forms of cancer, heart disease, and genetic
disease.
Genetic disease
A genetic disorder or disease is caused by one or more genetic mutations. It is often
inherited, but some mutations are random and de novo.
Hereditary or inherited disease
A hereditary disease is a type of genetic disease caused by genetic mutations
that are hereditary (and can run in families)
Human Genetics
The passing-down of traits from parent to child through genes, which are in chromosomes.

Genetic Code
A series of messages contained in the chromosomes. This code regulates cell functions by
way of directing the synthesis of cell proteins. The code corresponds to the structure of the
DNA. The code is transmitted to new cells during cell division
Genes
A locatable region of a genomic sequence, corresponding to a unit of inheritance. A
union of genomic sequences encoding a coherent set of potentially overlapping functional
products; i.e. genes are one long continuum (2007). Determine cell properties, both structure
and functions unique to the cell.
Genome
 Sum of all genes contained in a cell’s chromosomes
 Identical in all cells
 Not all genes are expressed in all cells
 Not all genes are active all the time
 May code for enzymes or other functional proteins, structural proteins, regulators of
other genes
Chromosomes
A chromosome is a thread like structures in the nucleus of the cell, Nucleus contains
DNA and carries the genetic material of a cell. Discovered by Waldeyer in 1876. In
prokaryotic cells, chromosomes consist entirely of DNA and are not enclosed in a nuclear
membrane. In eukaryotic cells, the chromosomes are found within the nucleus and are
composed of chromatin material which is chemically DNA and proteins.
• Chromones is the name given to these structures as they readily absorb dyes and
become colored
 Chromo means Color
 Soma means Body
• A certain number of chromosomes is characteristic of each species of plant and
animal. Human has 46 chromosomes in each somatic cell.

Females have two X chromosomes; their sex chromosomes are ‘XX’. Males have
one X and one Y, so are XY. As females are XX, they can only pass on the X
chromosome to their offspring. It’s the male’s chromosome that decides gender. If
a male pass on his X chromosome, the baby will be a girl, if he passes on his Y
chromosome, the baby will be a boy.
CHROMATIN MATERIA
• Chromatin is a complex of DNA and protein found in eukaryotic cells. Chromatic is a
complex combination of DNA, RNA, and Protein. The nucleosome is the unit of
chromatin
Sex chromosomes
 Genetic sex = composition of X and Y
 Large X: many genes, many activities
 Small Y: almost entirely male sexual diff.
 Female: XX, male XY
 One X randomly inactivated and nonfunctional after the first week of
embryonic development
 Same inactivated X in descendant cells
The Y Chromosome
• Fewer than two dozen genes
identified
• One is the master gene for
male sex determination
• SRY gene (Sex-determining
region of Y)
• SRY present, testes form
• SRY absent, ovaries form
The X Chromosome
• Carries more than 2,300
genes
• Most genes deal with
nonsexual traits
• Genes on the X
chromosome can be
expressed in both males and
females

Mitosis
Walther Fleeming observed the division of the cell, he noticed that during division,
nucleus passes through a series of changes, he called these changes as Mitosis. In this
type of cell division, the cell divides into 2 daughter cells. In each daughter cell, the
chromosome number is maintained at the same level as that in the parent cell. Mitosis
usually occurs in the somatic cells (body cells) and results in growth, healing of
wounds, etc.
 Interphase: DNA duplication to form chromatids just before mitosis
 Prophase: centriole migration, mitotic spindle
 Metaphase: chromosomes line up in the center, chromatids still joined at the
centromere
 Anaphase: chromosomes separate into sister chromatids
 Telophase: sister chromatids form new chromosomes, new nuclear
membranes form, cytoplasm divides
Meiosis
Meiosis was discovered in 1876, by a German biologist Oscar Hertwig. Meiosis is the
types of cell division, in which each daughter cell receives half the number of
chromosomes as the parent cell. It is also called reduction division as the diploid
number of chromosomes (2n) is reduced to haploid (n). Meiosis occurs is germs cells
during the process of sexual reproduction.
 First meiotic division interphase: duplication of chromosomes to form paired
chromatids
 Prophase 1 of meiosis: homologous chromosomes lie side by side over entire
length = synapse.
o Interchange of segments of homologous chromosomes = crossover.
o 2 Xs side by side just like the autosomes.
o X and Y end-to-end: no crossover.
 Metaphase 1: paired homologous chromosomes align at the equatorial plate
 Anaphase 1: homologous chromosome pairs migrate to opposite poles of the cell;
each chromosome is composed of two chromatids, the chromatids are not separated
 Telophase 1: two new daughter cells form;

o each contains half the chromosome number = reduction of chromosomes by
half; interchange of genetic material occurred during synapse
Second meiotic division = mitotic division
 Prophase 2: DNA does not replicate
 Metaphase 2: chromosomes align at the equatorial plate
 Anaphase 2: sister chromatids migrate separately
 Telophase 2: four haploid cells (half the normal number of chromosomes)
 In the parent cell, the chromosomes are in the form of homologous pairs. This paired
no of chromosomes is called diploid (2n), When chromosomes are not in pairs, their
no is called haploid (n). Fungi
GENETICS AND GENES
HEREDITY IS responsible for the continuity of life forms. Although offspring’s and
parents in a generation may look different, there is a basic similarity that runs from
generation to generation. Each generation transfer to the next, the instruction, required
for maintaining continuity of life. These instructions are in the form of chemical codes
which are present in DNA of an organism. These codes of information are called
genes which determine the expression of a certain character. A gene is a unit of
heredity in a living organism, the general basis for every character that appears in an
organism. Genetics is a branch of science in which we study the various process
which leads to our understanding of basic principles of inheritance
Inherit Diseases orGenetic Disease
Genetic inheritance is a basic principle of genetics and
explains how characteristics are passed from one generation to the next. Hereditary diseases
are disorders or diseases that are inherited genetically. They are also known as genetic
disorders or inherited diseases and may be passed on within the family if there is a mutant
gene present genetic disease is one that is caused by having defective DNA in some way. The
disease is present throughout the entire life of the individual.
Terminology;

 Hereditary (genetic): the result of chromosome abnormality or defective gene
 hereditary = derived from parents
 familial = transmitted in the gametes through generations
 congenital = present at birth (not always genetically determined - e.g.
congenital syphilis, toxoplasmosis)
! not all genetical diseases are congenital - e.g. Huntington disease - 3rd to 4th
decade of life
Modes of Inheritance
 Autosomal dominant (a dominant gene expressed in the heterozygous state)
 Autosomal recessive (expressed only in the homozygous individual, the disease only
if both alleles are abnormal,)
 Codominant (full expression of both alleles in heterozygous state)
 X-linked (usually affects male offspring; the abnormal X-linked gene acts as the
dominant gene when paired with the Y chromosome
Genetic Disorders
Types of Genetic Disorders

 Autosomal Recessive Genetic Disorders
 Autosomal Dominant Genetic Disorders
 Nondisjunction Genetic Disorders
 Sex-Linked Nondisjunction Genetic Disorders
Autosomal Dominant Diseases
A person may suffer from autosomal dominant disease when it gets an abnormal gene from
one parent that suffers from the same disease. When one of the parents has a mutant gene and
the other has a normal gene, the child has a 50% chance of inheriting the disorder. Dominant
inheritance means an abnormal gene from one parent can cause disease. This happens even
when the matching gene from the other parent is normal. A single, abnormal gene on one of
the autosomal chromosomes from either parent can cause certain diseases. One of the parents
will usually have the disease (since it is dominant) in this mode of inheritance. Only one
parent must have an abnormal gene for the child to inherit the disease.
 Both homozygotes and heterozygotes are affected
 usually heterozygotes (inherited from one parent)
 both males and females are affected
 transmission from one generation to the other
 50% of children are affected
Other Autosomal Dominant Diseases/Conditions:
 Achondroplasia
 Aniridia
 Polydactyly
 Adenomatous polyposis of the colon

Achondroplasia
Achondroplasia is an inherited disorder characterized by abnormally
short stature with disproportionately short limbs. Adult with achondroplasia may reach an
average height of 4 feet. This birth defect occurs due to a mutation of the FGFR3 gene and
cannot be treated.
Causes: Mutation in the FGFR3 gene
Frequency: 1 in 27,500 people
Symptoms: Short arms and legs, enlarged head,
Hereditary Hemochromatosis
Hereditary hemochromatosis is a genetic disease that causes
the body to absorb too much iron. Absorbed iron doesn’t leave the body but instead, it is
stored in the body organs, which can cause many health problems.
Down Syndrome
Down syndrome is also known as Trisomy 21 and it is caused by
inheritance of an extra chromosome 21. This condition causes a delay in the mental and
physical development of a child. This genetic disorder is rare and may be detected before a
child is born.
Autosomal Recessive Diseases
These genetic disorders are passed when both parents carry a defective gene.
 majority of mendelian disorders
 only homozygotes are affected, heterozygotes (parents) are only carriers
 25% of descendants are affected
 if the mutant gene occurs with low frequency - high probability in consanguineous
marriages
 the onset of symptoms often in childhood
 frequently enzymatic defect
 testing of parents and amnial cells

Tay - Sachs Disease
Tay – Sachs disease is a disorder of the nervous system that impairs
motor skills. it is a genetic disorder that results in the destruction of nerve cells in the brain
and spinal cord and causes mental retardation, blindness. Affected child experiences
symptoms such as delayed growth, dementia, irritability, and even paralysis
Polycystic Kidney Disease
This genetic disorder is very rare, and it is featured by a number
of cysts formed on the kidneys that can lead to kidney failure.
Usher Syndrome
Usher syndrome is inherited as an autosomal recessive disorder.
“Autosomal” means that men and women are equally likely to have the disorder and equally
likely to pass it on to a child of either sex. Usher syndrome is categorized into three major
types as types I, II and III.
 Type I is characterized by hearing loss or deafness that may be present from birth.
 Type II means that the affected person is born deaf but may lose a vision during
adolescence.

 Finally, type III manifests with hearing and vision loss that occurs when a person is
10 years old
Hereditary Fructose Intolerance
 Hereditary fructose intolerance (HFI) is an inborn error of fructose metabolism
caused by a deficiency of the enzyme aldolase B
 Symptoms of hereditary fructose intolerance include severe abdominal pain,
vomiting, and aversion to sweet foods.
Other autosomal recessive diseases include sickle cell anemia, albinism, cystic
fibrosis and phenylketonuria that affects a person's ability to digest the sugar
fructose.
Cystic fibrosis
 1:2000 live births - a most common lethal genetic disease in the white
population
 defect in the transport of chloride ions across epithelia - increased
absorption of Na+ and water to the blood
 widespread defect in the exocrine glands - abnormally viscid mucous
secretions
 blockage of airways, pancreatic ducts, biliary ducts
Gender Linked Diseases
Gender-linked disorders occur due to errors in X or Y chromosome. They include the
following;
Color Blindness
This condition causes eye nerve damage and affected person can’t
differentiate between colors. Color blindness means your eye doesn't see color the way it
should. Your eyes see differences in the light that comes in. Simple tasks such as
selecting ripe fruit, choosing to clothe, and reading traffic lights can be more
challenging. Color blindness is a usually a genetic (hereditary) condition (you are born
with it). Red/green and blue color blindness is usually passed down from your parents.

The gene which is responsible for the condition is carried on the X chromosome and this
is the reason why many more men are affected than women
Diagnostic method: Ishihara color test
8% of the male population and 4.5% of the population of the UK are color blind
and there are estimated to be over 250 million color blind people worldwide
Hemophilia
This disorder causes an inability of the blood to coagulate. This condition
affects only males. Hemophilia is a rare disorder in which your blood doesn't clot normally
because it lacks enough blood-clotting proteins (clotting factors). If you have hemophilia,
that means your body has problems stopping bleeding, both outside and inside your body
Hemophilia A comes from your genes. You can inherit it from your parents. Or it can happen
if a certain gene changes before you're born. This change is called a spontaneous mutation
The History of Hemophilia. ... Hemophilia has been called a "royal disease". This is
because the hemophilia gene was passed from Queen Victoria, who became Queen of
England in 1837, to the ruling families of Russia, Spain, and Germany. Queen Victoria's gene
for hemophilia was caused by spontaneous mutation. 1828 - Term “haemorrhaphilia” first
used. Later shortened to “hemophilia.”

Muscular Dystrophy
It is a muscle disorder that causes weakness of the skeletal muscles,
degeneration of the muscles and defective muscle proteins. Muscular dystrophy (MD) is a
group (30) of muscle diseases that results in increasing weakening and breakdown of skeletal
muscles over time.
The causes are genetic, A family history of muscular dystrophy will increase the chance of it
affecting an individual. There is currently no cure, but certain physical and medical
treatments can improve symptoms and slow the progression.
Polygenic Disorders
These genetic disorders are caused by multiple genes and may not be completely inherited
but represent a risk factor for certain diseases such as diabetes, heart disease, obesity, cancer,
and autoimmune disorders.

Cri Du Chat Syndrome
Most cases of cri du chat syndrome are not inherited. The chromosomal deletion usually
occurs as a random event during the formation of reproductive cells (eggs or sperm) or in
early fetal development. People with cri du chat typically have no history of the condition in
their family. About 10 percent of people with cri du chat syndrome inherit the chromosome
with a deleted segment from an unaffected parent. In these cases, the parent carries a
chromosomal rearrangement called a balanced translocation, in which no genetic material is
gained or lost. Balanced translocations usually do not cause any medical problems; however,
they can become unbalanced as they are passed to the next generation. A deletion in the short
arm of chromosome 5 is an example of an unbalanced translocation, which is a chromosomal
rearrangement with extra or missing genetic material. Unbalanced translocations can cause
birth defects and other health problems such as those seen in cri-du-chat syndrome.
Cri du chat syndrome - also known as 5p- syndrome and cat cry syndrome - is a rare genetic
condition that is caused by the deletion (a missing piece) of genetic material on the small arm
(the p arm) of chromosome 5
Caused
 Caused by deletion of part of the short arm of chromosome 5
 Results in an abnormally small head with a deficiency in cerebral brain tissue
 Widely spaced eyes and mental retardation
Treatment
Children born with this genetic condition will most likely require ongoing support
from a team made up of the parents, therapists, and medical and educational professionals to
help the child achieve his or her maximum potential.
Nondisjunction Genetic Disorders
When chromosomes don't separate properly during meiosis OR Nondisjunction is the failure
of homologous chromosomes or sister chromatids to separate properly during cell division
results in gametes w/ too many or few chromosomes.
 Downs syndrome/Trisomy 21

 Patau syndrome/Trisomy 13
 Edwards syndrome/Trisomy 18
Trisomy 21 / Down Syndrome
Down syndrome (DS or DNS), also known as trisomy 21, is a
genetic disorder caused by the presence of all or part of the third copy of chromosome21. It is
typically associated with physical growth delays, mild to moderate intellectual disability, and
characteristic facial features.
Causes: Third copy of chromosome 21
Other names: Down's syndrome, Down's, triso...
Diagnostic method: Prenatal screening, genetic ...
Symptoms: Delayed physical growth, character, Mental retardation, distinctive eyes, short
stature
Trisomy 13 – Patau syndrome
Trisomy 13, also called Patau syndrome, is a chromosomal
condition associated with severe intellectual disability and physical abnormalities in many
parts of the body. ... Due to the presence of several life-threatening medical problems, many
infants with trisomy 13 die within their first days or weeks of life
Symptoms
 defects of eye, nose, lip, and forebrain
 Polydactyly (more than 5 fingers or toes)
 hyperconvex fingernails (arches down)
 Only 18% survive the first year
 Survivors have severe mental defects
Trisomy 18- Edwards syndrome
Trisomy 18, also called Edwards syndrome, is a chromosomal condition associated with
abnormalities in many parts of the body

Symptom;
 Clenched hand
 Distinct patterns on the fingertip
 Low Arch Dermal - the crease on the tip the 5th finger is missing.
 80% die w/in the first two months
 Only 10% survive the first year
 Resuscitation (artificial breathing) often performed at birth
Sex-linked Nondisjunction Genetic Disorders
• A normal female has two X chromosomes. A normal male has an X and a Y
chromosome. transmitted by heterozygous mother to sons
 daughters - 50% carriers, 50% healthy
 sons - 50% diseased, 50% healthy
 Children of deceased father - sons are healthy, all daughters are
carriers
 Hemophilia A (defect of Factor VIII)
 Hemophilia B (defect of Factor IX)
 Muscle dystrophy (Duchen disease)
There are several disorders where additional sex chromosomes are present
 Turner syndrome
 Klinefelter syndrome
 Fragile-X syndrome
Turner syndrome
Turner syndrome (TS), also known as 45, X or 45, X0, is a condition in
which a female is partly or completely missing an X chromosome. Signs and symptoms vary
among those affected.

Other names: Ullrich–Turner syndrome; gonadal ...
Symptoms: Webbed neck, short stature, swollen ...
Diagnostic method: Physical signs, genetic test...
Causes: Missing X chromosome
Physical Characteristics;
 Short Stature
 Web neck
 Infertile
 Normal intelligence
 Low posterior hairline
 broad chest with widely spaced nipples
 elevated frequency of renal (kidney) and cardiovascular
anomalies
Klinefelter syndrome
Klinefelter syndrome (KS) also known as 47, XXY or XXY, is the set
of symptoms that result from two or more X chromosomes in males. The primary features are
infertility and small testicles. Often, symptoms may be subtle, and many people do not realize
they are affected.
 Other names: XXY syndrome, Klinefelter's syn...
 Causes: Two or more X chromosomes in males
 Frequency: 1:500 to 1:1,000 males
 Symptoms:
 Tall, thin relatively long legs
 appear normal until puberty
 Hypogonadism (sex hormones are not released)

 Infertile due to undeveloped sex organs
 significantly reduced IQ
Fragile X Syndrome
Fragile X syndrome is a genetic condition that causes a range of
developmental problems including learning disabilities and cognitive impairment. Usually,
males are more severely affected by this disorder than females. Affected individuals usually
have delayed development of speech and language by age 2.
Symptoms:
 In males, the lower portion of the X chromosome appears constricted in a
karyotype.
 Moderate mental retardation
 Fragile site - chromatin fails to condense during mitosis
 Females who carry the trait may also show symptoms
 long face with a prominent jaw, large prominent ears, high arched palate;
flattened nasal bridge; Prominent forehead
Chromosomal aberrations (cytogenetic disorders)
 alternations in the number or structure of chromosomes
 autosomes or sex chromosomes
 studied by cytogenetics
 cell cycle arrested in metaphase (colchicine) - staining by Giemsa method
(G-bands) - photographing - karyotype
 2 sets of 23 chromosomes
 22 pairs of autosomes, 2 sex chromosomes (XX or XY)

 cytogenetic disorders are relatively frequent! (1:160 newborns; 50% of
spontaneous abortions)
 Chromosomal aberrations (cytogenetic disorders)
Structural abnormalities
 breakage followed by loss or rearrangement
 deletion, translocation
Generally:
 loss of chromosomal material is more dangerous than gain
 abnormalities of sex chromosomes are better tolerated than
autosomal
 abnormalities of sex chromosomes sometimes symptomatic in adult
age (e.g. infertility)
 usually origin de novo (both parents and siblings are normal)
Clinical symptoms
 mental retardation (IQ 25-50)
 flat face + epicanthus
 congenital heart defects
 neck skin folds
 skeletal muscle hypotonia
 hypermobility of joints
 increased risk of acute leukemias
 mortality 40% until 10Y (cardiac complications)
Sex chromosomal disorders
 several karyotypes from 45(X0) to 49 (XXXXY) - compatible with survival
 normally - in females 1 of X is inactivated (all somatic cells contain Barr
body)
 ! male phenotype is encoded by Y

Classification of genetic diseases
Three groups of genetic diseases
 Disorders with multifactorial inheritance (polygenic)
 Monogenic (mendelian) disorders
 Chromosomal aberrations
1. Disorders with multifactorial inheritance (polygenic)
Multifactorial inheritance disorders mean that "many factors" (multifactorial) are
involved in causing a birth defect. The factors are usually both genetic and
environmental, where a combination of genes from both parents, in addition to
unknown environmental factors, produce the trait or condition
Symptoms:
 influence of multiple genes + environmental factors
 relatively frequent
 Diabetes mellitus (see Endocrine pathology)
 Hypertension (see Circulation)
 Gout (discussed here + see Crystals)
 Schizophrenia (Psychiatry)
 Congenital heart disease - certain forms (see Heart)
 Some types of cancer (ovarian, breast, colon) (see Neoplasms)
 often familial occurrence - the probability of disease is in 1st-degree
relatives about 5-10%; 2nd-degree relatives - 0,5-1%
Marfan syndrome (MFS)
Marfan syndrome (MFS) is a genetic disorder of the connective tissue.
The degree to which people are affected varies. People with Marfan tend to be tall and thin,
with long arms, legs, fingers, and toes. They also typically have flexible joints and scoliosis.

Causes: Genetic (autosomal dominant)
Symptoms:
 Tall stature with long slim limbs
 Low tone muscles
 Little subcutaneous or skin fat
 60% scoliosis
 Heart disorders (thought that Abraham Lincoln had this disorder)
2. Monogenic (mendelian) disorders
Mendel's studies of inheritance patterns in pea plants are a solid foundation for our current
understanding of single-gene diseases inhumans. Also called Mendelian or
monogenic diseases, these kinds of diseases are caused by mutations in one gene, and they
sometimes run in families. Scientists currently estimate that over 10,000 of human diseases
are known to be monogenic. Monogenic diseases are responsible for a heavy loss of life. The
global prevalence of all single gene diseases at birth is approximately 10/1000. In Canada, it
has been estimated that taken together, monogenic diseases may account for up to 40% of the
work of hospital-based paediatric practice (Scriver, 1995).
Examples include sickle-cell anemia, Tay–Sachs disease, cystic fibrosis, and xeroderma
pigmentosa. Single-Gene or monogenic diseases can be classified into three main categories:
 Autosomal dominant
 Autosomal recessive
 X-linked
OTHER INHERIT DISEASES
Thalassemia
Thalassemia is made of 2 Greek words; Thalassa means sea & Haem means blood1
Thalassemia is an inherited blood disorder which is caused by the weakening and
destruction of blood cells which leads to anemia. It is also caused by variant or missing

genes, which severely affect the making of hemoglobin protein, an essential ingredient,
which helps red blood cells carry oxygen. It is named so because this disorder was
originally found in like living on the shores of the Mediterranean Sea.
Cause: It is a genetically transmitted disease from parents to children
Symptom:
 A person defecting from this disease has a defective mechanism of producing
hemoglobin
 The defective hemoglobin cannot transport oxygen, this causes severe anemia
and the patient becomes very weak
 Blood tests can detect if a person is a carrier or if they have thalassemia
Solution: The blood of these patients needs to be replaced regularly with the normal
blood donor
Cystic Fibrosis
A genetic disorder in which the body produces abnormally thick mucus in the
lungs and intestines.
Sickle-Cell Disease
 A genetic disorder that affects the blood
 Caused by a mutation that affects the production of an important protein
called hemoglobin
 Hemoglobin is the protein in red blood cells that carries oxygen
 People with the disease suffer from lack of oxygen in the blood and
experience pain and weakness
Hemophilia
A genetic disorder in which a person’s blood clots very slowly or not at all

 People with the disorder do not produce one of the proteins needed for normal
blood clotting
 A disorder that is carried on the recessive allele on the X chromosome (sex-linked
gene)
 More common in males than females
Huntington’s Disease
 A genetic disorder that is caused by a dominant allele
 Every individual who inherits the allele develops the disease
 A person with the disease has a 50% chance of passing it on
 Fatal; symptoms do not usually appear until a person is over 30 years old
 Causes the gradual breakdown of cells in the brain
Down Syndrome
 A genetic disorder that is the result of an extra copy of chromosome 21
 Result of an error during meiosis-chromosomes failing to separate
 People with Downs have a distinctive physical appearance and have some
degree of mental retardation; heart defects are also common
The most common conditions that tend to run in families:
Heart disease:coronary atherosclerosis, high blood pressure, hyperlipidemia
Diabetes; Diabetes is a disease in which your blood glucose, or blood sugar, levels are
too high.
Cancer: retinoblastomas, colon, stomach, endometrium, lung, bladder, breast, skin
(melanoma)
Color Blindness; Color blindness is a genetic condition caused by a difference in how
one or more of the light-sensitive cells found in the retina of the eye respond to certain

colors. These cells, called cones, since wavelengths of light, and enable the retina to
distinguish between colors
Neurological illnesses and disorders: Alzheimer’s disease, amyotrophic lateral sclerosis
(Lou Gehrig’s disease), Gaucher’s disease, Huntington’s disease, multiple sclerosis,
neurofibromatosis, Parkinson’s disease, Tay-Sachs disease, Tourette’s syndrome
Mental illnesses and behavioral conditions: alcoholism, anxiety disorders, attention
deficit disorder, eating disorders, manic depression, schizophrenia
Other genetic diseases:cleft lip and cleft palate, clubfoot, cystic fibrosis, Duchenne
muscular dystrophy, galactosemia, hemophilia, Hurler’s syndrome, Marfan’s syndrome,
phenylketonuria, sickle cell disease, Thalassemia
Medical conditions with genetic links: arthritis, asthma, baldness, migraine
headaches, obesity, periodontal disease, speech disorders
Solution
Today doctors use tools such as amniocentesis and karyotypes to help detect genetic
disorders
No genetic illness can be cured. Hemophiliacs can inject clotting factors, and people with
PKU can adjust their diet, but they can never get rid of their genes. The best way to deal
with genetic disorders is to prevent them through screening. Simple blood tests can detect
the gene for sickle-cell anemia
Your health care provider can then give you individualized and specific education about how
to:
 Check regularly for the disease.
 Follow a healthy diet.
 Get regular exercise.
 Avoid smoking tobacco and too much alcohol.
 Get specific genetic testing that can help with diagnosis and treatment.

Conclusion
Our body is made up of billions of cells inside each cell is our genetic material. a
chromosome is the packaging of the genetic material we usually have 23 pairs of
chromosomes and we inherit one copy from mother and one from father. if we unwind
chromosomes we can identify genes, genes are basic building block that makes protein
genes are like blueprint to make a machine and proteins are like the individual
components of that machine Protein makes us who we are and help us grow and function
properly Our genetic material is made up of DNA (Deoxy ribo nuclei acid), Is the very
long chains of four chemical letters (adenine guanine thymine cytosine) That combine to
make our genetic code We all have small variations in genetic code gene variation are
like spelling errors
E.g. there is a T instead of a C a variation in a gene that makes it faulty or not working
properly is called mutation.Faulty genes occur commonly simply through chance They
have to occur in one individual for the first time at some stage they are not related to
anything a parent could have cost or prevent in any way they occur because the process
that replicates and divides our genes so we can pass them on to the next generation is
complex and mistakes occur for each gene we have 2 copies one copy comes from
mother and the other copy comes from father In an autosomal recessive condition an
individual needs both copies of the gene to be faulty for a condition to develop The
parents of the child usually carry one faulty gene of the gene pair they are healthy carries
it is estimated that every individual is a healthy carrier of several faulty genes but a
recessive condition occurs only when both individuals in a couple happen to carry the
same faulty gene when Healthy carriers have children there are three possible outcomes.
One the child inherits both faulty gene copies and has the condition to the child inherits
only one faulty gene copy and is a healthy carries like his/her Parents three a child
inherits both working copies of the gene so each time healthy carriers have children
There is a one in four twenty five percent chance that their child could inherit both faulty
gene copies and develop the condition when an individual with a recessive condition has
children their children will usually all be healthy carriers of the condition their children
could develop; the condition if their partner happens to be a carrier of a faulty gene but
this would be a rare occurrence brothers and sisters of a healthy carrier could also be
healthy carrier themselves

References
 http://www.sciencemadesimple.co.uk/curriculum-blogs/biology-blogs/what-is-dna
 https://basicbiology.net/micro/genetics/genetic-inheritance
 https://www.slideshare.net/jayreimer/4genetics-types-of-inheritance-by-cj
 https://www.nidcd.nih.gov/health/usher-syndrome
 http://www.colourblindawareness.org/colour-blindness/causes-of-colour-blindness/
 https://en.wikipedia.org/wiki/Color_blindness
 (https://www.hog.org/handbook/article/1/3/the-history-of-hemophilia
 https://www.medicalnewstoday.com/articles/187618.php
 https://www.genome.gov/19517558/learning-about-cri-du-chat/
 https://en.wikipedia.org/wiki/Down_syndrome
 https://www.familytreemagazine.com/premium/common-genetically-inherited-diseases/
 https://www.yourgenome.org/facts/what-is-a-mutation
 http://www.sciencemadesimple.co.uk/curriculum-blogs/biology-blogs/what-is-dna
 https://ghr.nlm.nih.gov/condition/trisomy-13
 https://openoregon.pressbooks.pub/mhccmajorsbio/chapter/complex-multifactorial-
disorders/
 //economictimes.indiatimes.com/articleshow/64075389.cms?utm_source=contentofintere
st&utm_medium=text&utm_campaign=cppst
 https://www.medicalnewstoday.com/articles/263489.php
 https://www.genome.gov/FAQ/Genetics-Disease-Prevention-and-Treatment
 https://www.who.int/genomics/public/geneticdiseases/en/index2.html
 https://www.who.int/genomics/public/geneticdiseases/en/index2.html
 https://en.wikipedia.org/wiki/Turner_syndrom
 https://ghr.nlm.nih.gov/condition/fragile-x-syndrome

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