Two XX males diagnosed in childhood. Endocrine, renal, and laboratory findings.

Two prepubertal boys with bilateral cryptorchidism were identified as 46,XX after nuclear sexing studies in several tissues. Gonadal histology and chromosome studies suggested that true hermaphroditism or mosaicism were unlikely. Xg blood grouping was informative in one patient. Accepting paternity, this suggested either that both Xs were maternal, with loss, for example, of the male determining Y chromosome, or that the paternal X chromosome did not express, probably because of a deletion, the allele for the positive Xg blood group. The patients had normal thyroid stimulating hormone reserves but subnormal responses to human chorionic gonadotrophin stimulation, and may need hormonal replacement at puberty. Both had renal anomalies. We suggest that chromosome analysis is essential when cryptorchidism, hypospadias, or microgenitalia are found and that an intravenous pyelogram is desirable.