Y sex-determining region: A region on the Y chromosome that determines the sex of the individual. This region goes by the symbol SRY (sex region Y). SRY is necessary and sufficient for male sex determination. It is the testis-determining factor.
Mutations in SRY give rise to XY females with gonadal dysgenesis who appear to be normal females at birth, but at puberty do not develop secondary sexual characteristics (breasts, etc.), do not menstruate, and have streak (fibrous) gonads without eggs. There is a high incidence of neoplasia (gonadoblastoma and germinoma) in the streak gonads.
Translocation (transfer) of the part of the Y chromosome containing SRY to the X chromosome results in XX males -- individuals who have XX sex chromosomes but appear male.
SRY resides in chromosome band Yp11.3 and encodes a transcription factor that is a member of the high mobility group (HMG)-box family of DNA binding proteins.