Complementation studies with clinical and biochemical characterizations of a new variant of multiple sulphatase deficiency.
A patient with a new variant of multiple sulphatase deficiency (MSDv) is reported. Unlike the usual type, onset was late and progress was slow. The phenotypic changes were those usually seen in multiple sulphatase deficiency but much milder. Cytoplasmic accumulations were found in skin fibroblasts, and urinary mucopolysaccharides and sulphatides were high. Arylsulphatases A, B and C (ASA, B and C), heparan N-sulphatase sulphoiduronate sulphatase, and N-acetylgalactosamine 6-sulphatase all had low activity in lymphocytes and cultured skin fibroblasts. Complementation for ASA activity was found in hybrids between MSDv and metachromatic leukodystrophy (MLD) as well as between multiple sulphatase deficiency (MSD) and MLD. Complementation for ASC activity was also seen in hybrids between MSDv and X-linked ichthyosis (XLI), and between MSD and XLI. However, neither ASA nor ASC activity increased in hybrid cells of MSDv and MSD. These results suggested that the mutations of MSDv and of MSD were allelic, although of different phenotypes.