A state of ambiguity regarding the assigning of sex or gender, usually because of ambiguity of the genital organs at birth. There is male intersex if the karyotype is 46,XY, female intersex if it's 46,XX. Incorporates hermaphrodism and pseudohermaphrodism, terms that are not much used outside the US.

Complete or partial resistance to the action of androgens in the body's tissues. Prevents or limits the development of male characteristics in the developing fetus, resulting in intersex.

(CAH) Enlargement and abnormal function of the adrenal glands, usually from before birth, owing to a genetically determined, partial block in the production of cortisol, the adrenal glands' main hormone, resulting in overproduction of subsidiary hormones, including androgens, tending to virilise the female fetus, which can present at birth with intersex. In mild forms does not manifest until puberty, when the symptoms of oligomenorrhea and hirsutism mimic those of polycystic ovary syndrome. See also serum 17-hydroxyprogesterone.

(DHT) The most active male sex hormone or androgen; formed in target tissues from testosterone (which is the main form of androgen circulating in the blood). Testosterone must be converted to DHT before it can do its job (the enzyme for which is 5-alpha reductase, and a deficiency of which is a cause of intersex.

Synonymous with intersex, except that intersex also includes true hermaphrodism.

17-hydroxyprogesterone is formed from progesterone in the adrenal glands (mostly as an intermediary substance on the way to making the adrenal's main hormone, cortisol) and in the ovaries (on the way to making androgens and estrogens). A congenital lack of one or other of the enzymes needed to make cortisol in the adrenal causes androgens to be made instead, in turn causing hirsutism and oligomenorrhea in women, maybe with the polycystic ovary syndrome (in mild cases), or (in severe cases) causing intersex at birth. The adrenal glands enlarge in an attempt to maintain production of cortisol (hence congenital adrenal hyperplasia, CAH). An inappropriately high level of 17-hydroxyprogesterone in serum is diagnostic of CAH.

A state of intersex in which the karyotype is male (i.e. 46,XY), the gonads are testes (hence also male), but the body is completely unresponsive to testosterone and to its metabolite dihydrotestosterone, so it develops in the female way, with a normal vulva and vagina apparent at birth, and with normal development of the breasts at puberty. Because the testes still secrete anti-Mullerian hormone, there's no uterus. Invariably these children are raised as girls, normal except for their primary amenorrhea and their infertility. Specialist medical supervision is needed, because there is an increased risk of cancer in the abnormal gonads. Synonymous with androgen insensitivity syndrome (complete form).

An individual with a gender identity that is opposite to that conventionally associated with his or her biological sex. Not to be confused with intersex or with sexual preference.

Intersex when tissue typical of an ovary and a testis is found in the one person. The genital organs can appear to be normal female, normal male, or somewhere in between. Intersex states where there are either normal ovaries or normal testes (but not both) are sometimes called pseudohermaphrodism.