ATI RN
Pediatric Genetics Questions
Question 1 of 5
Cystic fibrosis is the most common autosomal recessive disorder in caucasian children with an occurrence of 1 in 2000 in Caucasian populations and about 1/22 carriers in Caucasian populations. Assuming that these data are applicable to a Norwegian community in U.S.A comprising of 16000 people, the percentage of all the CF genes hidden carriers and in patients in this community are respectively:
Correct Answer: B
Rationale: Allele frequency q² = 1/2000 → q = 1/44.7, p = 43.7/44.7. Carriers = 2pq ≈ 1/22 (4.45%). Affected = q² = 0.05%. Total CF alleles: 2(8) + 356 = 372. Carriers’ alleles = 356/372 = 97.8%, affected = 16/372 = 2.2%.
Question 2 of 5
The practical way to visualize a karyotype of a suspected very large chromosomal deletion, is to:
Correct Answer: B
Rationale: Metaphase (B) is ideal for karyotyping as chromosomes are condensed and aligned, allowing visualization of deletions. Rationale: Colcemid arrests cells in metaphase, enabling clear banding and structural analysis, unlike anaphase (separating) or S phase (replicating).
Question 3 of 5
The figure depicts two possible graphs of an assumed population genetic diversity. In comparison to each other:
Correct Answer: D
Rationale: Crossing over in meiosis increases diversity (D is correct). Rationale: Crossing over (prophase I) shuffles alleles, favoring higher diversity (graph B likely shows more variation). A and B are false (crossing over is meiotic), C reverses logic.
Question 4 of 5
A patient with Klinefelter syndrome can be seen as:
Correct Answer: A
Rationale: Klinefelter is 47, XXY male (A). Rationale: Extra X causes male infertility, tall stature, etc. Females cannot be XXY (SRY on Y); 45, X is Turner syndrome (female).
Question 5 of 5
A child person with clinical features that include: cardiovascular, brain with neurological, renal, gastrointestinal, respiratory, and skeletal malformations, craniofacial abnormalities such as prominent occiput, hand and feet anomalies including clenched hand. This patient is most probably affected with:
Correct Answer: A
Rationale: Trisomy 18 (Edwards syndrome, A) fits. Rationale: Clenched hands, multiple organ defects, and craniofacial issues (e.g., prominent occiput) are hallmark Edwards features. Down (B, D) lacks these specifics; Turner (C) differs (e.g., lymphedema).