ATI RN
Genetic Pediatric Questions
Question 1 of 5
A mentally retarded 15-year-old boy is found to have macroorchidism and large, prominent ears. He most likely has
Correct Answer: D
Rationale: Fragile X syndrome is characterized by intellectual disability, macroorchidism (enlarged testicles), and large ears, especially in males due to its X-linked inheritance. Cerebral giantism (Sotos syndrome) involves overgrowth but not typically macroorchidism. Acromegaly is a pituitary disorder seen in adults. Hypothyroidism doesn’t cause these features, and trisomy 21 (Down syndrome) presents with distinct facial features but not macroorchidism.
Question 2 of 5
A 1-year-old presents with a disease that is classically an autosomal recessive trait (such as cystic fibrosis). The father is tested and, with 99% confidence, he is demonstrated to be negative for the carrier state. The most likely explanation is
Correct Answer: B
Rationale: If the father isn’t a carrier, the child could inherit two mutant alleles from the mother via uniparental isodisomy (both chromosomes from one parent). This explains an autosomal recessive trait without paternal contribution. Dominant mutation, paternal isodisomy, imprinting, or mitochondrial inheritance don’t fit.
Question 3 of 5
Which of the following DNA changes is pathogenic:
Correct Answer: D
Rationale: Mutations (sequence changes), epigenetic modifications (gene expression alterations), and variants (polymorphisms or mutations) can all be pathogenic depending on context—e.g., disrupting gene function or regulation.
Question 4 of 5
A European couple with diagnosis of hearing loss in father's brother in autosomal recessive variant. What is the probability to have an AFFECTED FETUS? Knowing that the carrier frequency of this variant in the European population is around 1/30.
Correct Answer: D
Rationale: Father’s brother affected means father has 2/3 chance of being a carrier (since parents are carriers). Mother’s carrier chance is 1/30 (population frequency). If both are carriers (2/3 × 1/30 = 2/90), child has 1/4 chance of being affected. Total = 2/90 × 1/4 = 1/180.
Question 5 of 5
A patient with retinoblastoma has a single tumor in one eye; the other eye is free of tumors:
Correct Answer: D
Rationale: Unilateral, single-tumor retinoblastoma is typically sporadic (two somatic hits), not heritable (which often presents bilaterally or multifocally). Parents are unaffected in sporadic cases.