Genetics
MRCPCH Part 1
Dr M Bhat
Demonstration
Genes are on chromosomes
Types of Genetic Disorder
• Chromosomal
• Single Gene
• Contiguous gene disorder
• Multifactorial (polygenic)
Metaphase spread
Normal Male 46 XY
Normal Female 46 XX
Down Syndrome
Trisomy 21
47, XX, +21
Chromosome abnormalities
• Autosomal trisomies
• Sex Chromosome abnormalities
• Deletions / duplications / inversions / ri...
Translocations
Down Syndrome
Trisomy 21
47, XX, +21
Nondisjunction
Abnormal Meiosis
Parents’ Cells
Normal Meiosis
Gametes (sex cells)
Zygotes (Fertilized Cells)
Trisomy 21 Mo...
Down’s Syndrome
• 95% Trisomy 21
• 3% Translocation
• 2% Mosaic
Baby with Down’s Syndrome
Hand / foot having Down’s Syndrome
Eye with Down’s Syndrome
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...
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Types of Genetic Disorder - Genetics MRCP 1 - 123Doc Education

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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/

Published in: Health & Medicine, Technology

Types of Genetic Disorder - Genetics MRCP 1 - 123Doc Education

  1. 1. Genetics MRCPCH Part 1 Dr M Bhat Demonstration
  2. 2. Genes are on chromosomes
  3. 3. Types of Genetic Disorder • Chromosomal • Single Gene • Contiguous gene disorder • Multifactorial (polygenic)
  4. 4. Metaphase spread
  5. 5. Normal Male 46 XY
  6. 6. Normal Female 46 XX
  7. 7. Down Syndrome Trisomy 21 47, XX, +21
  8. 8. Chromosome abnormalities • Autosomal trisomies • Sex Chromosome abnormalities • Deletions / duplications / inversions / ring chromosomes • Translocations -Reciprocal -Robertsonian
  9. 9. Translocations
  10. 10. Down Syndrome Trisomy 21 47, XX, +21
  11. 11. Nondisjunction Abnormal Meiosis Parents’ Cells Normal Meiosis Gametes (sex cells) Zygotes (Fertilized Cells) Trisomy 21 Monosomy 21
  12. 12. Down’s Syndrome • 95% Trisomy 21 • 3% Translocation • 2% Mosaic
  13. 13. Baby with Down’s Syndrome
  14. 14. Hand / foot having Down’s Syndrome
  15. 15. Eye with Down’s Syndrome
  16. 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
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