ATI RN
Common Pediatric Genetic Disorders Questions
Question 1 of 5
A 6-month-old with unilateral retinoblastoma has genetic testing performed. The results of the tumor and blood analysis at the RBI locus are shown below. What is the likelihood that a future sibling WILL NOT DEVELOP retinoblastoma? (R is Arginine and X is stop codon)
Correct Answer: B
Rationale: Unilateral retinoblastoma without family history is often sporadic (non-heritable), with two somatic hits in the tumor. Blood normal (no germline mutation) means siblings have population risk (<1/20,000), approximated as >99% chance of not developing it.
Question 2 of 5
A child with cleft palate, a heart defect, and extra fifth fingers is found to have 46 chromosomes with extra material on one homologue of the chromosome 5 pair. This chromosomal abnormality is best described by which of the following terms?
Correct Answer: D
Rationale: Extra material on one chromosome 5 with a total of 46 chromosomes indicates an unbalanced rearrangement (e.g., partial duplication), causing phenotypic abnormalities.
Question 3 of 5
The most common lethal genetic disease in the United States is:
Correct Answer: B
Rationale: Cystic fibrosis is the most common lethal autosomal recessive disorder in the U.S., with significant morbidity and mortality.
Question 4 of 5
The genetic disease cystic fibrosis is caused by a defective allele that:
Correct Answer: C
Rationale: Cystic fibrosis is caused by mutations in the CFTR gene, leading to a defective chloride channel protein, affecting mucus and sweat production.
Question 5 of 5
If a fragment of a chromosome breaks off and then reattaches to the original chromosome but in the reverse direction, the resulting chromosomal abnormality is called:
Correct Answer: B
Rationale: An inversion occurs when a chromosome segment is reversed in orientation after breaking and reattaching.