A 6-year-old boy who has mental retardation secondary to fragile X syndrome has been admitted to hospital with a mitral valve prolapse

Question

A health care worker who is providing care for the family should have which of the following statements as part of her knowledge base around the disease?
A)
The common pattern of inheritance is an affected mother who carries one normal and one mutant allele.
B)
The boy's mother had a 100% chance of transmitting the defective gene to her son.
C)
Genes of the boy's Y chromosome can be affected in addition to the X chromosome.
D)
The boy will pass the gene to all his future daughters who will become carriers.

Answer 1

Ans:
D

Feedback:

When the affected son procreates, he transmits the defective gene to all of his daughters, who become carriers of the mutant gene. The most common pattern of inheritance for fragile X syndrome is an unaffected mother carrying one normal and one mutant allele. The Y chromosome is not affected.