SRY - Effect Upon Anatomical Sex

Effect Upon Anatomical Sex

Since its discovery, the importance of the SRY gene in sex determination has been extensively documented:

• Humans with one Y chromosome and multiple X chromosomes (XXY, XXXY etc.) are usually males.
• Individuals with a male phenotype and an XX (female) karyotype—XX male syndrome—have been observed; these males have the SRY gene in one or both X chromosomes (or possibly on an autosome), moved there by chromosomal translocation. (However, these males are infertile.)
• Similarly, there are females with an XXY or XY karyotype. These females have no SRY gene in their Y chromosome, or the SRY gene exists but is defective (mutated).