ATI RN
Genetic Disorders in Pediatrics Questions
Question 1 of 5
Neurofibromatosis Type 1 regarded as one of the most common AD disorders but many affected individuals have features so mild that they are never diagnosed. Of the following, the MOST likely cause of such phenomena is
Correct Answer: B
Rationale: Variable expressivity (B) explains mild NF1 phenotypes (e.g., few café-au-lait spots vs. tumors). Rationale: Penetrance (A) is near 100% in NF1; UPD (C) is unrelated.
Question 2 of 5
Fragile X syndrome (FRAX) is the most common cause of inherited intellectual disability. The individual who manifest the disease may have the number of trinucleotide repeat of CGG in the region Xq 27 of
Correct Answer: D
Rationale: Fragile X full mutation is >200 CGG repeat. Rationale: Normal is <45 (A), premutation 55–200 (B, C, D); >200 causes methylation and intellectual disability.
Question 3 of 5
Of the following, the study that is MOST useful in diagnosis of an aneuploidy is
Correct Answer: A
Rationale: Karyotyping (A) directly visualizes aneuploidy (e.g., trisomy 21). Rationale: FISH (B) confirms specific regions; microarray (C) detects microdeletions, not whole chromosome changes.
Question 4 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 5 of 5
All the following are characteristic features of Williams syndrome EXCEPT
Correct Answer: D
Rationale: Williams syndrome (7q11.23 deletion) includes hypercalcemia (A), elfin face (B), blue irides (C), and friendly personality (E); IQ is typically low (D is false). Rationale: Mild intellectual disability is common.