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Steroid sulphatase deficiency is a feature of recessive X-linked ichthyosis (RXLI) that causes the accumulation of sulphated steroids (SS) in various organs and cells. In a previous study, we detected elevated cholesterol sulphate (CS) and dehydroepiandrosterone sulphate (DHEAS) serum levels in a group of 15 RXLI patients selected in a narrow age range. In the present study both CS and DHEAS serum levels were qualitatively and quantitatively determined using gas-chromatographic analysis in a group of 33 RXLI patients ranging in age from 3 to 70 years. The levels of CS and DHEAS were significantly increased in all patients. Variations in SS were related both to patients' ages and clinical course of the disease; Serum SS levels start to increase in early infancy, peak at puberty, remain elevated in adults and decrease slightly in the elderly.

The metabolic basis of X-linked ichthyosis is a deficiency of steroid sulphatase, a microsomal enzyme which removes sulphate groups from sulphated steroids. We report on a carefully controlled group of 15 patients with recessive X-linked ichthyosis, selected in a narrow age range (22-33 years), in whom, through the use of gas chromatographic analysis and conventional radioimmunoassay, we have measured not only elevated serum cholesterol sulphate levels but also significantly elevated serum dehydroepiandrosterone sulphate levels. The latter finding has been controversial in previous reports. We believe that the radioimmunoassay procedure generally used should be held responsible for such controversy since it often gives rise to false positive and/or false negative values. Gas chromatography, although more exacting, appears to be far more reliable for the assessment of elevated serum dehydroepiandrosterone.

The authors report on the occurrence of ocular abnormalities in X-linked ichthyosis (XLI) patients, in their carrier mothers and in healthy volunteers who served as controls. The diagnosis of XLI was based on: (1) demonstration of steroid sulfatase deficiency in cultured skin fibroblasts; (2) lack of hybridization of patient's deoxyribonucleic acid (DNA) with specific steroid sulfatase complementary DNA probe; (3) electrophoretic mobility of plasma lipoproteins. Cholesterol sulfate plasma levels were also determined. The incidence of corneal opacities was the same in XLI patients and in their carrier mothers (23.7 and 24.3%, respectively). Neither other corneal nor ophthalmological alterations were found. Moreover, in XLI patients the plasma levels of cholesterol sulfate were about twenty times higher than in controls. Our findings demonstrate that ocular changes do not seem to be an absolute criterion for a definite diagnosis of XLI and the fact that the pathogenesis of corneal opacities is not due to an accumulation of cholesterol sulfate, but rather that this compound probably induces physicochemical changes of the corneal tissue properties.