Pathogenic mutations in TBX5 cause Holt-Oram syndrome which includes cardiovascular (atrial septal defect, hypoplastic left heart syndrome), chest (Absent pectoralis major muscle) and skeletal anomalies (vertebral anomalies, triphalangeal thumb and carpal bone anomalies). The TBX5 phenotypic effect is related to which concept:

Correct Answer: C

Rationale: Pleiotropy (C) describes one gene affecting multiple traits. TBX5 mutations cause diverse effects (heart, chest, skeleton), fitting this concept. Rationale: Unlike reduced penetrance (variable expression), sex-limited (gender-specific), or multifactorial (many factors), pleiotropy explains TBX5’s broad impact.

Correct Answer: D

Rationale: Nonspecific vaginitis treatment focuses on hygiene (A), sitz baths (B), mild soaps (C), Metronidazole (D). is unnecessary. Rationale: Metronidazole treats bacterial vaginosis (e.g., Gardnerella), not nonspecific irritation; hygiene measures address the cause.

Correct Answer: C

Rationale: Bitemporal hemianopsia and hyperprolactinemia indicate a pituitary lesion; head CT (C) or MRI confirms this. Rationale: Head imaging detects prolactinomas; abdominal/pelvic scans (A, B) and biopsy (D) are irrelevant to pituitary pathology.

Correct Answer: D

Rationale: Autosomal dominant traits affect autosomes (A), require one mutant allele (B), have 50% inheritance (C), and allow male-to-male transmission (D). Male:female ratio is ~1:1, not 2:1 Rationale: Sex bias suggests X-linked, not AD.

Correct Answer: D

Rationale: Adrenoleukodystrophy (D) is XLR; CF (A), CAH (B), and Gaucher (C) are AR; sickle cell (E) is AR. Rationale: ALD affects X chromosome (ABCD1 gene).