Dr. med. Dirk Manski



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46,XX Males

Definition

46,XX male sydrome is a chromosomal disorder in men with a male phenotype and a 46,XX karyotype (Ergun-Longmire et al, 2005). It is sometimes called de la Chappelle-syndrome (first description in 1964).

Epidemiology

The incidence of the 46,XX male syndrome is 1:20.000.

Etiology

In 80%, the 46,XX male syndrome is caused by a translocation of a Y-chromosome fragment on the paternal X chromosome. As a necessary gene for testicular development, the SRY gene was identified. In 20% of the 46,XX male syndrome· the SRY gene translocation is not detectable. In these cases, changes of the SRY-dependent genes are most likely responsible, such as activating mutations.

Signs and Symptoms of 46,XX Males

46,XX males are phenotypically and psychosexually male. They have a normal physique and normal external genitalia. Small testes, symptoms of hypogonadism, gynecomastia or hypospadia (10%) may be present. 46,XX male syndrome causes infertility (2% of infertile men).

Diagnostic Work-Up

Laboratory Tests:

Hypergonadotropic hypogonadism. Semen analysis reveals azoospermia.

Karyotyping:

46,XX

Testicular Biopsy:

In proven 46,XX karyotype, testicular biopsy is not indicated. Histology will show tubular hyalinization and lack of spermatogenesis.

Treatment of 46,XX Male Syndrome

Androgen replacement in proven hypogonadism. Treatment of gynecomastia.







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References

Ergun-Longmire, B.; Vinci, G.; Alonso, L.; Matthew, S.; Tansil, S.; Lin-Su, K.; McElreavey, K. & New, M. I.
Clinical, hormonal and cytogenetic evaluation of 46,XX males and review of the literature.
J Pediatr Endocrinol Metab, 2005, 18, 739-748


  Deutsche Version: 46,XX Männer