Testis determining factor

Testis-determining factor (TDF), also known as sex-determining region Y (SRY) protein, is a DNA-binding protein (also known as gene-regulatory protein/transcription factor) encoded by the SRY gene that is responsible for the initiation of male sex determination in humans. SRY is an intronless sex-determining gene on the Y chromosome in therians (placental mammals and marsupials); mutations in this gene lead to a range of sex-related disorders with varying effects on an individual's phenotype and genotype.

TDF is a member of the SOX (SRY-like box) gene family of DNA-binding proteins. When complexed with the SF1 protein, TDF acts as a transcription factor that can upregulate other transcription factors, most importantly SOX9. Its expression causes the development of primary sex cords, which later develop into seminiferous tubules. These cords form in the central part of the yet-undifferentiated gonad, turning it into a testis. The now-induced Leydig cells of the testis then start secreting testosterone, while the Sertoli cells produce anti-Müllerian hormone. SRY gene effects normally take place 6–8 weeks after foetus formation and inhibits the female anatomical structural growth in males. It also works towards developing the dominant male characteristics.

SRY (disambiguation)

SRY is the HUGO Gene Nomenclature Committee assigned symbol for the mammalian gene "sex determining region Y".

SRY is an abbreviation that can also mean:

Haplogroup R-M167

In human genetics, Haplogroup R-M167 is a Y-chromosome haplogroup which is a subdivision of haplogroup R1b defined by the presence of the marker M167, also known as SRY2627.

Distribution

The first author to test for this marker (long before current haplogroup nomenclature existed) was Hurles in 1999, who tested 1158 men in various populations. He found it relatively common among Basques (13/117: 11%) and Catalans (7/32: 22%). Other occurrences were found among other Spanish, Béarnais, other French, British and Germans.

In 2000 Rosser et al., in a study which tested 3616 men in various populations also tested for that same marker, naming the haplogroup Hg22, and again it was found mainly among Basques (19%), in lower frequencies among French (5%), Bavarians (3%), Spanish (2%), Southern Portuguese (2%), and in single occurrences among Romanians, Slovenians, Dutch, Belgians and English.

In 2001 Bosch described this marker as H103, found in 5 Basques and 5 Catalans. However a study in 2005 of Spanish Basques found lower levels of this haplogroup than those recorded in Basques by the earlier studies - only four samples out of the 168 tested.