Deletion of distal promoter of VCXA in a patient with X-linked ichthyosis associated with borderline mental retardation.

BACKGROUND: X-linked ichthyosis (XLI) is caused by deficiency of steroid sulfatase (STS) activity. About 90% XLI patients have large deletions involving the entire STS gene and flanking regions. Recently, VCXA, which is located approximately 0.7Mb telomeric to the STS gene, was reported as a candidate gene for mental retardation (MR) in patients with XLI.

OBJECTIVE: To delineate the X-chromosomal deletion of a XLI patient with borderline mental retardation.

METHODS: We carried out FISH analysis to show that the whole STS gene is deleted, and PCR analysis for fine-scale deletion mapping.

RESULTS: The deleted segment is approximately 1.6Mb in size, and includes the entire STS and VCXB1 genes. VCXA itself is intact, but its promoter is deleted.

CONCLUSION: A deletion that includes the VCXA promoter is associated with borderline mental retardation in a patient with XLI.