Deletion of exons 1-5 of the STS gene causing X-linked ichthyosis

X-linked ichthyosis is an inherited disorder due to steroid sulfatase defic iency. It is clinically characterized by dark, adhesive, and regular scales of the skin. Most X-linked ichthyosis patients present large deletions of the STS gene and flanking markers; a minority show a point mutation or part ial deletion of the STS gene. In this study we analyzed the STS gene in a f amily with simultaneous occurrence of X-linked ichthyosis and ichthyosis vu lgaris. X-linked ichthyosis diagnosis was confirmed through steroid sulfata se assay in leukocytes using 7-[H-3]-dehydroepiandrosterone sulfate as a su bstrate. Exons 1, 2, 5, and 6-10, and the 5' flanking markers DXS1130, DXS1 139, and DXS996 of the STS gene were analyzed by polymerase chain reaction. X-linked ichthyosis patients of the family (n = 4 males) had undetectable levels of STS activity (0.00 pmol per mg protein per h). The DNA analysis s howed that only exons 6-10 and the 5' flanking markers of the STS gene were present. We report the first partial deletion of the STS gene spanning exo ns 1-5 in X-linked ichthyosis patients.