46,X-Y

Last reviewed 01/2018

The chromosomal abnormality of 46,X-Y interchange involves the appearance of a male phenotype despite the individual having a female karyotype. Sensitive marker techniques reveal most of the female karyotypes to have a transfer of the male Yp region to the Xp region of one of the female sex chromosomes. This transfer in paternal meiosis results in the testis-determining factor residing on the wrong chromosome. The recurrence risk is minimal.

Clinically, the sufferer may present for the investigation of infertility, or after the female predicted by prenatal diagnosis turns out to have a male phenotype.

Patients are sterile, having the endocrine features of Klinefelter's syndrome such as small testes and therefore reduced testosterone levels. Unlike Klinefelter's, intelligence is normal, and there is no skeletal disproportion.