Testis determining factor

Testis-determining factor (TDF) is a protein encoded by the SRY gene located on the Y chromosome in humans. TDF is a transcription factor that is critical for the development of male gonads, specifically the testes.

Function

TDF is responsible for initiating the process of sex determination in the developing embryo. It acts by upregulating the expression of other genes that lead to the differentiation of the bipotential gonad into a testis. This process involves the activation of Sertoli cells, which are essential for testis formation and the subsequent production of male hormones such as testosterone.

Genetic Mechanism

The presence of the SRY gene on the Y chromosome is the primary determinant of male sex in humans. During embryogenesis, the expression of TDF triggers a cascade of genetic events that result in the development of male characteristics. In the absence of TDF, the default pathway leads to the development of ovaries and female characteristics.

Clinical Significance

Mutations or deletions in the SRY gene can lead to disorders of sex development (DSDs), such as Swyer syndrome, where individuals have a 46,XY karyotype but develop as females due to the lack of functional TDF. Conversely, translocation of the SRY gene to an X chromosome can result in 46,XX testicular disorder, where individuals develop male characteristics despite having two X chromosomes.

See Also

• Sex-determination system
• Y chromosome
• SRY gene
• Gonadal dysgenesis

External Links

• SRY gene information at NCBI
• TDF protein information at UniProt

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