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you have to think about each child individually, doesn't matter what the siblings have. The question states what are the odds of the child getting the disease. So regardless of the other siblings it still is Mom (1/2) dad (1/2) which makes it 1/4 AR
But how do we know that the parents are heterozygous for the mutation
we know that the parents have to be heterozygous Aa X Aa because on a 2x2 table, the only way the daughter could be homozygous for an AR is by having both parents be carriers (Aa) so the question was asking what are the chances the sister has the same alleles (aa) and there is only a 25% of having the same alleles.
Sexual dysfunction [desire based = libido] can be due to drug side effects [antihypertensives], per first aid.
Per, 1stAid's endocrine section: "excessive amounts of prolactin associated with ↓libido .
This goes together with our sexual dysfunction with "antihypertensives."
Only logical synthesis I can think of:
thiazide = ↑prolactin = ↓libido + galactorrhea. It would also make sense since we are dealing with an expected to be post-menopausal female [milk production would have to be due to exogenous source].
Dug into my lecture notes and found the following: beta-blockers and thiazides cause sexual dysfunction.
I also like sam1's explanation. We're reaching here, but its the best I can do.
Mayo clinic shows clear or bloody nipple discharge as side affect of Thiazides. But doesnt state milky discharge.