46,XX testicular difference of sex development

46,XX testicular difference of sex development is a condition in which individuals with two X chromosomes in each cell, the pattern typically found in females, have a male appearance. People with this condition have male external genitalia. They generally have small testes and may also have other features such as undescended testes (cryptorchidism) or the urethra opening on the underside of the penis (hypospadias). A small number of affected people have external genitalia that do not look clearly male or clearly female.

At puberty, most affected individuals require treatment with the male sex hormone testosterone to induce development of male secondary sex characteristics such as facial hair and deepening of the voice (masculinization). Hormone treatment can also help prevent breast enlargement (gynecomastia). Adults with this condition are usually shorter than average for males and are unable to have children (infertile).

Other names

46,XX testicular disorder of sex development; 46,XX testicular DSD; nonsyndromic 46,XX testicular disorder/difference of sex development; XX male syndrome

Inheritance pattern

Autosomal dominant

Related genes

SRY; NR5A1; WT1; SOX9; SOX3

Source: MedlinePlus Genetics, U.S. National Library of Medicine.