X-linked ichthyosis

X-linked ichthyosis is relatively common disorder. Since it is nonprogressive and nondebilitating, many of the patients with this disease escape medical detection. Many become frustrated with the lack of improvement in their condition by medical management and so are lost to further follow-up. The genetics of this condition are reasonably well understood. Recent investigations have associated this disorder with absence of the microsomal enzyme, steroid sulfatase. This genetically determined enzymopathy results in defective estrogen production during fetal life and in ichthyosis during postnatal life. Genetic studies have established that the gene that determines this disorder is located in an unusual and interesting portion of the human X chromosome. This will undoubtedly result in our further understanding of the mechanisms by which genes and chromosomes are regulated and controlled. The availability of a specific enzymatic assay for steroid sulfatase deficiency using cultured skin fibroblasts now makes it possible to diagnose this disorder in individuals at any point during life. Further studies to elucidate the pathophysiologic mechanism by which this enzyme defect produces the skin disorder should advance our basic understanding of the biology of skin and may eventually provide effective therapy for patients with X-linked ichthyosis.