[Clinical and genetic study of a 46, XX man with occult mosaicism ].

OBJECTIVE: To describe a 46,XX male with a hidden mosaicism. METHOD: Clinical, hormonal and genetic findings are presented. RESULTS: The patient was a normal phenotypic male with a bilateral testicular volume of 10 ml. Hypergonadotropic hypogonadism (elevated serum concentrations of FSH and LH, and normal serum concentration of testosterone) without gynecomastia was found. Final karyotype was a 46,XX/47,XX + mar mosaic, with 3% of studied cells containing an abnormal SRY positive Y chromosome. CONCLUSION: XX males karyotype must include a great number of metaphases in order to ascertain a definitive genetic diagnosis.