Androgen Insensitivity versus 5 alpha Reductase Deficiency

[tyagee]

46 XY is the normal male genotype, but can result in a female phenotype in patients with
androgen insensitivity or 5-alpha-reductase deficiency.

any1 knows how to differentiate between 2 entities AI and 5alpha reductase deficiency ?

[Novobiocin]

Development of pubic hair, and other androgenic hair of face, torso, and limbs in 5 alpha reductase deficiency is normal.
No hair in androgen insensitivity

[stfidel]

very difficult to differentiate... especially for the subtypes of AIS when the patient is prepubertal...but a strong clue for 5 alpha reductase deficiency is .....the penis eventually develop but only at puberty....some researchers call 5 alpha reductase deficiency "the penis at 12 disease"...referring to the pubertal event...


The high levels of testosterone (due to the enzyme def) at puberty...overcomes the body's requirement and selectivity for DHT...hence ambiguous genitalia becomes a real definite penis......

[Novobiocin]

Androgen Insensitivity Syndrome patients does not have functional androgen receptors so they'll present with Primary amenorrhoea at puberty.

5-alpha reductase deficiency patients have increased production of testosterone which binds intact receptors at puberty and will begin to display secondary male sex characteristics along with Primary amenorrhoea.

Labs:

AIS: high [LH, estrogen, testosterone]
5-ARD: high(or normal) [LH], normal [estrogen, testosterone]

[flakiedoodles]

Originally Posted by tyagee

any1 knows how to differentiate between 2 entities AI and 5alpha reductase deficiency ?

1.androgen insensitivity is a lack of response to all androgens from fetal period despite high circulating androgen levels.
thus the child is chromosomally XY but due to lack of androgenic effects the wolffian ducts degenerate, the external genitalia is feminized.
P.S the MIF from d SRY gene causes degeneration of the mullarian ducts also.
**** AIS can be Complete, partial or mild. the above description is for complete and is the tested subtype.

2. 5 alpha reductase deficiency results in failure of conversion of TESTosterone to DiHydroTestosterone. DHT is responsible for inutero formation of the male EXTERNAL genitalia, hair follicles and prostate in adults

similarities: XY chromosome, undescended testes, male pseudohermaphroditism.
Differences
AIS (complete) 5HT def
no internal genitals at all-----------------male internal genitals
Appears female thru out life------------develops [email protected] puberty(due to test)
high TESTosterone levels---------------normal TEStosterone levels