Mapping of a new SGBS locus to chromosome Xp22 in a family with a severe form of Simpson-Golabi-Behmel syndrome

Abstract

Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked overgrowth syndrome with associated visceral and skeletal abnormalities. Alterations in the glypican-3 gene (GPC3), which is located on Xq26, have been implicated in the etiology of relatively milder cases of this disorder. Not all individuals with SGBS have demonstrated disruptions of the GPC3 locus, which raises the possibility that other loci on the X chromosome could be responsible for some cases of this syndrome. We have previously described a large family with a severe form of SGBS that is characterized by multiple anomalies, hydrops fetalis, and death within the first 8 wk of life. Using 25 simple tandem- repeat polymorphism markers spanning the X chromosome, we have localized the gene for this disorder to an ~6-Mb region of Xp22, with a maximum LOD score of 3.31 and with LOD scores