Mutations in a gene called RSPO1 result in female to male sex reversal, according to a study to be published in the November 2006 issue of Nature Genetics.
Giovanna Camerino and colleagues studied an Italian family in which four brothers were identified as having two X chromosomes -- the female complement of sex chromosomes. Such female to male sex reversal is extremely rare, and is usually accompanied by translocation of the male sex-determining gene SRY from the Y chromosome to one of the other chromosomes. In this family, however, the SRY gene is not present, suggesting another genetic cause of sex reversal. The authors identified mutations in RSPO1 -- which encodes R-spondin1, a member of a small family of proteins that are secreted by cells -- in all of the brothers. This study represents the first time that the mutation of a single gene has been shown to cause complete female to male sex reversal in the absence of SRY, and shows that RSPO1 is also an essential ovary-determining gene.
Giovanna Camerino (University of Pavia, Italy)
Abstract available online.
(C) Nature Genetics press release.
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