Var said:
Doesnt gear cause hairloss in women??? I wonder if the PS's could have caused it.
It depends on your genetics.
Baldness, or more commonly, male pattern baldness is inherited in a
polygenic fashion. or a trait inherited by either or both of the parents. It may be a
sex limited due to incomplete expression and penetrance but not
X linked inheritance like color blindness. Male pattern baldness is a classic example of how inheritance pattern for something as
simple as balding
cannot be explained by pure Mendelian genetics anymore.We used to think it was inherited in an autosomal dominant manner but we now know it is inherited from both parents and can have
incomplete penetrance thus, have varying levels of expression in the person who carries the gene. Ie: you can have the gene, but you don't go bald or you can look michael jordan if the environment is right.
Since the hormonal environment has to be right, it makes sense that men express it at an early age due to high levels of testosterone and byproduct hormones. Women can express it early if they have untreated congential adrenal hyperplasia (where the adrenal glands overproduce male hormones) or a ovarian tumor that produces testosterone, or use androgenic hormones
and carry the gene.
The hormonal mileu of the women approaches that of men after menapause (higher ratio of testosterone to estrogen) (Remember, our adrenal glands continue to make testosterone until death) so some women who carry the gene will start expressing it then. Also overactive or underactive thyroid can cause hair loss.
Intersting there is a racial preferrance. Androgenic alopecia is responsible for male pattern baldness in fifty percent of white men and women over 40 but the percentage is less in asians, blacks and lastly, American Indians. So the idea of
coinheritance (say a racial gene inherited with the balding gene ) may also be important.
Some people may not have the gene and still have age related miniaturization of the hair follicles and it can look like incomplete balding. These people probably won't respond to Propecia (a 5-alpha reducatse inhibitor) but might respond to Rogaine (don't really know the mechanism of action of the latter).
Rember, there are other causes of "cue ball" like non scarring alopecia called alopecia areata, alopecia totalis etc. which are not genetic disorders so much as
autoimmune conditions (like Lupus, Rheumatoid etc.)
Most of all, remember,
we have yet to isolate the specific gene or set of genes exclusively responsible for male pattern baldness!!!!
Interesting, that some women exhibit the female pattern hair loss (diffusse thinning ) and some the M shaped male pattern of (early loss in temporal area etc.) Female pattern hair loss may be a different mechanism and responds to estrogen and or Rogaine but not to Propecia unlike male pattern hair loss where you can use the Propecia in these women. In addtion, it may be that women have the 5-HT enzyme expressed in a diffuse manner rahter than concentrated in the M distribution on the men. I would have to look into that.
