Endocrine Abstracts

Introduction: The XX male syndrome occurs in 1 in 20,000 births. This syndrome results from crossover between the X and Y chromosomes, which transfers the sex-determining region of the Y chromosome to the X chromosome. They lack the azoospermia factor region of the Y chromosome, which is essential for spermatogenesis; thus causing infertility.

Case Description: 34-year-old gentleman was referred to endocrinology clinic for infertility and semen analysis showing azoospermia. He had symptoms of hypogonadism and examination showed normal male phenotype with small testes. Investigations showed hypergonadotropic hypogonadism, hence Klinefelter’s syndrome was suspected and karyotyping requested. Karyotype analysis revealed a 46,XX karyotype. Further testing by (QF)-PCR was consistent with the presence of two X chromosomes but also indicated the presence of material from the distal region of the Y chromosome short arm. This included the SRY (sex-determining region Y) gene locus and FISH studies for the X chromosome centromere and SRY confirmed a picture of two X chromosomes, one of which contained SRY. A review of the karyotype showed a consistent dark band at the distal end of the short arm of one X chromosome, representing band Yp11.3 from the Y chromosome which contains the SRY gene locus. Therefore, one copy of the X chromosome in this patient’s karyotype is actually a derivative X chromosome resulting from a translocation between the short arms of an X chromosome and a Y chromosome. Diagnosis and prognosis of infertility was explained to the patient with genetic counselling. He was then started on testosterone replacement.

Discussion: XX males are phenotypically similar to Klinefelter’s males. They have small testes, azoospermia, infertility, and seminiferous tubule hyalinization. They both present with hypergonadotropic hypogonadism. However, men with this disorder have below average height and do not have intellectual impairment unlike Klinefelter’s males.