5-a reductase deficiency vs. androgen insensitivity syndrome?

[swtiepie711]

Would anyone be kind enough to explain the difference b/w these?

My thought process:
- 5-a reductase deficiency: can't make DHT, but you will make TDF, AMH & Testosterone. DHT, according to a UW question explanation (I think that's where I got this from), accounts for development of male external genitalia (penis, prostate). All else will be male.

- AIS: won't respond to testosterone or DHT. Make TDF (so have testes), make AMH (so no female internal genital structures), but w/o responding to testosterone won't develop Wolffian ducts (so no male internal structures or external structures).

So in a question stem - how would they distinguish? Would they have to rely on 5-ARD being "penis @ 12" or AIS being "older teenage female who isn't menstruating?"? Do 5-ARD NOT have a rudimentary vagina?

Confused in part because in looking into it online: "Most individuals with 5-ARD are identified in the neonatal period because of ambiguous genitalia. However, some of these children are misdiagnosed as having partial or complete androgen insensitivity syndrome (AIS), which can produce almost identical phenotypes. As noted above, some patients with 5-ARD virilize partially at puberty"

Thanks to anyone kind enough to clarify!

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[Depakote]

My take:

Both syndromes lack the ability of androgens to act cause the development of the male external genital tract so you default to female external genitalia.

AIS patients will never have functional androgen receptors so they'll present with amenarche at puberty. 5-alpha reductase deficiency patients will have increased production of testosterone which binds intact receptors at puberty and will begin to display secondary male sex characteristics along with amenarche. I would say this is the best way to distinguish the two syndromes and probably the way they'd ask the question given that they'll both present as phenotypic females prior to puberty.



EDIT: I do believe both AIS and 5-alpha reductase deficiency can lead to ambiguous genitalia... but the extremes (which is probably what you'd see in a test) would be a phenotypic external sex that doesn't match the XY sex.

 

[SomeDoc]

Would anyone be kind enough to explain the difference b/w these?

So in a question stem - how would they distinguish? Would they have to rely on 5-ARD being "penis @ 12" or AIS being "older teenage female who isn't menstruating?"? Do 5-ARD NOT have a rudimentary vagina?

You'll have to use labs in conjunction w/ clinical features presented:
AIS: high [LH, estrogen, testosterone]
5-ARD: high(or normal) [LH], normal [estrogen, testosterone]