A healthy mother is married to a man who has a roberstonian 14,21 balance. What is the possibility to have a baby with down syndrome?

Correct Answer: D

Rationale: 1/6 ( missing in OCR) is correct. Rationale: 45, XY, t(14;21) produces 6 gametes: normal, t(14;21), 14, 21, null 14, null 21. With 46, XX, only 21+t(14;21) yields 47, +21 (Down), 1/6 chance.

Correct Answer: B

Rationale: Marfan syndrome’s multiple effects (eye, skeleton, heart) from FBN1 mutations exemplify pleiotropy (B). Rationale: One gene mutation (FBN1) affects connective tissue across systems, unlike allelic heterogeneity (different mutations, same phenotype) or anticipation (worsening generations).

Correct Answer: C

Rationale: Galactorrhea (milky discharge), amenorrhea, and headaches suggest hyperprolactinemia, possibly from a pituitary adenoma. Serum prolactin level (C) is the most useful initial test. Rationale: Pregnancy tests (A, B) are relevant but less likely given Tanner stage 2 and no sexual history implied; prolactin directly assesses the suspected cause, unlike estrogen (D) or LH (E, not listed).

Correct Answer: A

Rationale: Prepubertal vulvovaginitis features discharge (B), erythema (C), and pruritus (D), but exacerbation at puberty (A) is incorrect as it’s more common pre-puberty due to low estrogen. Rationale: Masturbation (E) may contribute but isn’t a defining feature; puberty increases estrogen, reducing incidence.

Correct Answer: B

Rationale: Bromocriptine (B), a dopamine agonist, is first-line for prolactinomas, shrinking tumors and normalizing prolactin. Rationale: Surgery (A) is for large/non-responsive tumors; Ondansetron (C) treats nausea, phenothiazine (D) increases prolactin, and antidepressants (E) are unrelated.