The STAG2 gene encodes one of the core proteins of the cohesin complex, which has a central role in the cell biology of eukaryotes. It forms a ring to entrap topologically chromosomes. The gene is located on X chromosome and undergoes inactivation.
The clinical picture of STAG2 germinative variants varies with the nature of the mutation: loss-of-function variants, missense variants and gene duplications: (1) Loss-of-function variants consist of a multisystem disorder that may include holoprosencephaly, affect primarily heterozygous females and are believed to be lethal in males with a 46,XY karyotype.
(2) Missense mutations have been reported twice: in a family with six affected males connected through healthy females and one isolated case with an unaffected mother.
(3) Gene duplications have been found as part of the so-called Xq25 duplication. In these cases, the main clinical manifestations are intellectual deficiency and facial hypotonia; Inheritance is X-linked.
Prevalence is unknown.
STAG2