Pedigree chart & autosomal inheritance
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This document defines a pedigree chart and discusses Mendelian inheritance patterns. It explains that a pedigree chart diagrams a family history showing genetic statuses. There are four main types of inheritance: autosomal dominant, autosomal recessive, X-linked, and Y-linked. Autosomal dominant requires only one affected gene where the disease is expressed in each generation. Autosomal recessive requires two affected genes where parents are carriers and have a 25% chance of an affected child in each pregnancy. The document provides examples of diseases that follow autosomal dominant and recessive inheritance patterns.
Pedigree chart & autosomal inheritance
- 1. Pedigree chart Dr.Rajprasath.R Senior resident Department of Anatomy JIPMER
- 2. Definition Diagram of family history indicating normal & affected individuals, their relationship to the proband & their status with respect to a particular genetic disorder
- 3. Symbols used
- 6. What is inheritance? • Passage of genes from parents to offspring • Pair of genes in 23 pairs of chromosomes • One of pair goes to one gamete Chromosome Gene
- 7. Single gene disorders • Due to mutation or change in single gene • Affected gene is passing to the next generation (inheritance)
- 8. Types of inheritance • Based on location & expression of disease • Autosomal inheritance • Sex chromosomal inheritance (X-linked) • Dominant • Recessive location Expression of disease
- 9. Expression of disease.. • Dominant – only one gene is affected-disease expressed • Recessive – disease expressed only if both genes are affected • Symbols indicating
- 10. - Affected gene - Normal gene Disease expressed Dominant Disease not expressed Recessive- carrier Recessive Disease expressed / Dominant 2 3 1 Homozygotes Heterozygotes
- 12. Autosomal dominant • One or both of the parents are always affected • 50% chance of children get affected • Both sexes are equally affected • All generations are affected • Normal children do not transmit the disease • E.g. Achondroplasia Marfan’s syndrome Neurofibroma
- 13. Parents Gametes Autosomal dominant inheritance Affected Affected Unaffected At conception
- 14. How to draw AD Pedigree chart
- 16. Autosomal recessive • Parents are healthy carriers • 25% chance for children getting affected • E.g. Cystic fibrosis Phenylketonuria Sickle cell disease Tay-sachs disease
- 18. How to draw AR Pedigree chart
- 20. Summary • What is inheritance? • Different Modes of inheritance • How to draw a pedigree chart? • How to diagnose an inheritance pattern from pedigree chart • Few points about autosomal inheritance
- 21. THANK YOU