Natural Sex Change in Humans
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Several medical conditions can result in a natural sex change in humans, where the appearance at birth is somewhat, mostly, or completely of one sex, but changes over the course of a lifetime to being somewhat, mostly or completely of the other sex. The overwhelming majority of natural sex changes are from a female appearance at birth to a male appearance after puberty, due to either 5-alpha-reductase deficiency (5alpha-RD-2) or 17-beta-hydroxysteroid dehydrogenase deficiency (17beta-HSD-3). A relative handful of male to female changes have been reported, and the etiologies of these are not well understood.
Genetic females (with two X chromosomes) with congenital adrenal hyperplasia lack an enzyme needed by the adrenal gland to make the hormones cortisol and aldosterone. Without these hormones, the body produces more androgen, a type of male sex hormone. This causes male characteristics to appear early (or inappropriately).
Genetic males (with one X and one Y chromosome) with androgen insensitivity syndrome is resistant to male hormone androgen. As a result, the person has some or all of the physical characteristics of a woman, despite having the genetic makeup of a man. The degree of sexual ambiguity varies widely in persons with incomplete AIS. Incomplete AIS can include other disorders such as Reifenstein syndrome which is associated with breast development in men.
Read more about this topic: Sex Change
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