Steroid sulfatase deficiency in Japanese patients: characterization of X-linked ichthyosis by using polymerase chain reaction.

X-Linked ichthyosis (XLI) due to deficiency of steroid sulfatase (STS) of which gene consists of 10 exons is an inherited skin disorder. The gene, mRNA and protein of STS were examined in six Japanese patients with XLI. Neither the mRNA nor the enzyme protein was detected in a patient. The results of Southern analysis using STS cDNA as a probe indicated that all the patients examined exhibited large deletions of the STS gene. When exon 1 and the exon 10 of the STS gene were amplified by polymerase chain reaction using patients' genomic DNA as templates, no product was detected in all the patients examined. These observations suggest that most XLI in Japanese patients is caused by an extensive deletion of the STS gene as was demonstrated in Caucasian patients. The PCR method in the present study is useful for the diagnosis of XLI in prenatal and postnatal subjects.