User:Dvassallo2020/XY sex-determination system

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Autosomal Sex Reversal through SOX9

Article body
The SRY gene is necessary for sex determination, but is not sufficient. This means that it is required in the process of sex determination, but it is not all that is required. Other genes are required aswell for sex determination such as SOX9, which is an autosomal gene also involved in sex determination, and contains a transcription factor that is required for the formation of testis. The SRY gene is known to be present in XY humans and absent in XX humans, but humans with the gene coding of XX can sometimes have an extra copy of the SOX9 gene, resulting in male development without the SRY gene being present. From a cellular perspective, the SOX9 gene is essential for male development because the protein binds to a promotor site on the Amh gene which is required for the development of the male phenotype. In mammals, SOX9 and SRY are both present and work together. SRY is activated first, and then proceeds to activate SOX9 to further the development of a male. In other vertebrates, SRY is not present but SOX9 is and becomes activated to further the development of a male. For this reason, the SOX9 gene is the central gene of sex determination.