46,XX SRY-negative true hermaphrodite siblings.
The sex-determining region on the Y chromosome (SRY) gene guides male sexual development. However, individuals with sex reversal syndrome (46,XX males and 46,XX true hermaphrodites) lack the SRY gene and yet can still develop testes. We present 2 siblings with XX true hermaphroditism. Most cases of sex reversal syndrome are sporadic; however, reports have been published of familial occurrence, suggesting that 46,XX maleness and 46,XX true hermaphroditism are actually different manifestations of the same disorder of gonadal development, likely an autosomal dominant mutation with variable penetrance or an X-linked mutation.