Two XX male brothers.

Two brothers with XX male syndrome with penoscrotal hypospadias are reported. Chromosomal analysis of cells from the peripheral blood, skin, and testes revealed a normal female karyotype in both subjects. Biopsy of both testes in the brothers showed histological features of normal immature testes and no evidence of ovarian structures. Neither vagina, uterus nor fallopian tubes could be detected either by exploratory laparotomy or retrograde urethrography. Results of endocrine studies on serum gonadotropins (LH and FSH) and testosterone levels as well as their responses to LH-RH and hCG stimulation tests were normal for age. Studies of various genetic markers, including the Xg blood type and erythrocyte enzymes, were performed in the probands and their parents. Possible explanations for the paradoxical occurrence of testes in XX males and for the familial occurrence are discussed.