Partial Androgen Insensitivity Syndrome refers to a number of medical conditions that cause the Androgen receptors to mutate. In a similar fashion to jigsaw puzzles, male sex hormones cannot bond completely to the receptor, and so only a partial virilisation occurs (as opposed to Complete Androgen Insensitivity Syndrome where there is absolutely no virilisation)

There are 7 grades from 1 (appearing male) to 6 and 7 (appearing female). Mild feminisation occurs during puberty when the unused testosterone is converted into oestrogen.

Grade 1 PAISers appear male but with very little or no effect during puberty.

Grade 2 PAISers appear male with a hypospadic penis

Grade 3 to 4 have the labia fused to form the beginnings of a scrotal sack and an enlarged clitoris.

Grade 5 has the labia partially fused with an enlarged clitoris

Grade 6 appears female

Grade 7 appears female but with so little effect of androgen that pubic hair fails to develop. This is Complete Androgen Insensitivity Syndrome.

Any grade can self identify as male, female, or somewhere inbetween.

Because of the act testosterone has on developing healthy bone tissue, hormone replacement may be necessary to prevent osteoperosis, as well as to develop secondary sexual characteristics in the desired direction.

Many PAISers have their diagnosis withheld from them and are surgically altered at a young age to resemble normal male or female children. This can have damaging consequences. See Intersexed and Hermaphrodite.