Genomic Imprinting, Mosaicism & Anticipation — Medical Genetics & Genomic Disorders

Genomic Imprinting, Mosaicism & Anticipation MCQs: practice questions

Sample Genomic Imprinting, Mosaicism & Anticipation multiple-choice questions from Medical Genetics & Genomic Disorders.

1. What is the key genetic principle illustrated by Prader-Willi and Angelman syndromes?

   • A. All deletions have identical effects
   • B. The same chromosomal deletion can produce different phenotypes depending on parental origin
   • C. Only maternal chromosomes are expressed
   • D. Only paternal chromosomes are expressed
   • E. Chromosome number never affects phenotype

2. Which chromosome carries the fragile X gene defect described by Mader?

   • A. Chromosome 21
   • B. Chromosome 5
   • C. Y chromosome
   • D. Chromosome 7
   • E. X chromosome

3. Which parent-of-origin mechanism can cause different phenotypes from the same deletion?

   • A. Mitosis
   • B. Translation
   • C. Crossing-over
   • D. Genomic imprinting
   • E. Nondisjunction

4. How many Barr bodies are typically present in an XX cell?

   • A. One
   • B. Four
   • C. Zero
   • D. Two
   • E. Three

5. What is mosaicism?

   • A. A type of inheritance
   • B. A type of trisomy
   • C. A mutation in every cell
   • D. Presence of only one chromosome
   • E. Presence of genetically or functionally different cell populations within one individual

6. Which statement about an imprinted allele is correct?

7. What is genomic imprinting?

8. Which phenomenon is best illustrated by different tissues expressing different X chromosomes?

9. Which syndrome is associated with paternal transmission of the relevant chromosome 15 deletion?

10. When are genomic imprints reset?

11. What is the relationship between repeat expansion and disease severity described by the concept of anticipation?

12. What does parent-of-origin expression mean?

13. What molecular mechanism is associated with genomic imprinting?

14. Which disorders are specifically described as showing anticipation?

15. What example of mosaicism is discussed by Mader?

16. Which syndrome is associated with maternal transmission of the relevant chromosome 15 deletion?

17. Which term best describes the inheritance-related increase in repeat number across generations?

18. How many Barr bodies are expected in an XY cell?

19. Which gene product is absent in fragile X syndrome according to Mader?

20. Why does X inactivation produce mosaicism in females?

21. What happens to the repeat number during anticipation?

22. Which phenomenon describes an increase in trinucleotide repeats in successive generations?

23. How can mosaicism arise?

24. When are genomic imprints established?

25. What determines which parental allele is expressed in genomic imprinting?

26. What is the normal-to-premutation transition in fragile X syndrome based on repeat number?

27. Why do calico cats show patches of different colors?

28. What is a Barr body?

29. What is the full-mutation threshold for fragile X syndrome in Mader?

30. How many Barr bodies are expected in an XXX cell?