Types of Genetic Disorder, as part of the Genetics MRCP 1 course. These are slideshows only. The demonstration with video presentation and explanation that goes along with these slides, as well as free example exam questions and the paid full e-lecture can be viewed at https://www.123doc.com/electures/genetics/

1. Genetics
MRCPCH Part 1
Dr M Bhat
Demonstration

2. Genes are on chromosomes

3. Types of Genetic Disorder
• Chromosomal
• Single Gene
• Contiguous gene disorder
• Multifactorial (polygenic)

4. Metaphase spread

5. Normal Male 46 XY

6. Normal Female 46 XX

7. Down Syndrome
Trisomy 21
47, XX, +21

8. Chromosome abnormalities
• Autosomal trisomies
• Sex Chromosome abnormalities
• Deletions / duplications / inversions / ring
chromosomes
• Translocations
-Reciprocal
-Robertsonian

9. Translocations

10. Down Syndrome
Trisomy 21
47, XX, +21

11. Nondisjunction
Abnormal Meiosis
Parents’ Cells
Normal Meiosis
Gametes (sex cells)
Zygotes (Fertilized Cells)
Trisomy 21 Monosomy 21

12. Down’s Syndrome
• 95% Trisomy 21
• 3% Translocation
• 2% Mosaic

13. Baby with Down’s Syndrome

14. Hand / foot having Down’s Syndrome

15. Eye with Down’s Syndrome

16. Risk of Down’s Syndrome in relation to
maternal age
Maternal age at delivery Risk (live birth)
All ages 1/650
20 1/1500
30 1/900
40 1/110
45 1/45