ATI RN
Pediatric Genetic Questions
Question 1 of 5
Variants in tumor suppressors on the genetic level are----and on the phenotypic level are:---
Correct Answer: A
Rationale: Tumor suppressor mutations are recessive genetically (both alleles must be lost), but phenotypically dominant (one hit predisposes to cancer via second hit).
Question 2 of 5
Allele:
Correct Answer: D
Rationale: An allele is a variant form of a gene at a specific locus on a chromosome.
Question 3 of 5
Which of the following is the proper cytogenetic notation for a female with Down syndrome mosaicism?
Correct Answer: D
Rationale: Mosaicism in a female with Down syndrome is written as 47,XX,+21 (trisomy 21) / 46,XX (normal), indicating two cell lines.
Question 4 of 5
Why is sickle cell disease so called?
Correct Answer: C
Rationale: Sickle cell disease is named for the sickle-shaped red blood cells caused by abnormal hemoglobin under low oxygen (not strictly pH), leading to their characteristic shape.
Question 5 of 5
Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls?
Correct Answer: D
Rationale: DMD is X-linked recessive. Females (XX) need two mutant alleles to be affected (rare), while males (XY) need only one, explaining the male predominance.