ATI RN
Genetic Disorders in Pediatrics Questions
Question 1 of 5
A young parents with Down syndrome baby with Robertsonian translocation. Both did a chromosomal karyotype study. Of the following the MOST likely result is
Correct Answer: B
Rationale: Maternal Robertsonian translocation (e.g., t(14;21)) is more common in DS (B). Rationale: Maternal age and translocation risk skew higher; one parent is typically the carrier.
Question 2 of 5
FISH in genetic testing is best described as
Correct Answer: D
Rationale: Fluorescence In Situ Hybridization (FISH) uses fluorescent probes to locate specific DNA sequences on chromosomes, identifying gene locations or chromosomal abnormalities. It doesn’t involve RNA prep, enzyme assays, buccal scraping, or fibroblast inhibition.
Question 3 of 5
Hypomelanosis of Ito is characterized by all of the following EXCEPT
Correct Answer: D
Rationale: Hypomelanosis of Ito features hypopigmented skin patterns, ocular/CNS issues, and mosaic chromosomal anomalies (autosomal or sex chromosomes). Skin fibroblast studies often show mosaicism, not normal chromosomes.
Question 4 of 5
A mutation leading to:
Correct Answer: B
Rationale: Advanced paternal age increases de novo mutations (e.g., in sperm), linked to conditions like hearing loss or autism. Trisomies (e.g., Edwards) and recessive disorders (e.g., CF, Tay-Sachs) are more tied to maternal age or inheritance, not paternal age.
Question 5 of 5
A unaffected couple who are first cousins request counseling regarding their risk of having a child with alpha-1-antitrypsin deficiency, a rare autosomal recessive trait. Their parents are unaffected. Their shared grandfather is affected with the disorder and their shared grandmother is heterozygous. What is the risk to their child of being HOMOZYGOUS FOR A VARIANT FOR THE CONDITION? (disregard the population carrier frequency)
Correct Answer: A
Rationale: Each parent has a 1/2 chance of inheriting the heterozygous allele from their grandmother (carrier). Probability both are carriers = 1/2 × 1/2 = 1/4. If both are carriers, the child has a 1/4 chance of being homozygous. Total risk = 1/4 × 1/4 = 1/16.