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

4. Mendelian Inheritance

5. 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

6. Single gene disorders Due to mutation or change in single gene Affected gene is passing to the next generation (inheritance)

7. Types of inheritance Based on location & expression of disease Autosomal inheritance Sex chromosomal inheritance (X-linked) Dominant Recessive location Expression of disease

8. Expression of disease.. Dominant – only one gene is affected-disease expressed Recessive – disease expressed only if both genes are affected Symbols indicating

9. - Affected gene - Normal gene Disease expressed Dominant Disease not expressed Recessive- carrier Recessive Disease expressed / Dominant 2 3 1 Homozygotes Heterozygotes

10. Autosomal inheritance

11. 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. A chondroplasia M arfan’s syndrome N eurofibroma

12. Parents Gametes Autosomal dominant inheritance Affected Affected Unaffected At conception

13. How to draw AD Pedigree chart

14. Autosomal recessive Parents are healthy carriers 25% chance for children getting affected E.g. Cystic fibrosis P henylketonuria S ickle cell disease Tay-sachs disease

15. Parents AUTOSOMAL RECESSIVE INHERITANCE Affected Unaffected (carrier) Unaffected Sperm/Eggs Unaffected (carrier)

16. How to draw AR Pedigree chart

17. 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

18. THANK YOU