Androgen insensitivity syndrome (AIS) is an intersex condition in which there is a partial or complete inability of many cells in the affected genetic male to respond to androgenic hormones.[1][2][3] This can prevent or impair the masculinization of male genitalia in the developing genetic male (chromosomal XY) fetus, as well as the development of male secondary sexual characteristics at puberty.[1][4] Clinical phenotypes range from a normal male habitus with mild spermatogenic defect or reduced secondary terminal hair; to a full female habitus despite the presence of a Y-chromosome.[1][5][6][7][8][9] Women (chromosomal XX) who are heterozygous for the AR gene have normal primary and secondary sexual characteristics; this female carrier will pass the affected AR gene to any child she has with 50% likelihood. AIS is the largest single entity that leads to 46,XY undermasculinized genitalia.
