Summary
Multiple sulfatase deficiency (MSD) or Austin's disease is an extremely rare lysosomal storage disease (only about 40 cases have been reported) characterized by a deficiency of all sulfatases whether lysosomal or not. It is due to a deficiency in formylglycine generating enzyme (FGE), located in the endoplasmic reticulum and required for the conversion of a cysteine in the active site into C-alpha- formylglycine. Transmission is autosomal recessive. Clinically, the disease combines variable proportions of clinical signs of metachromatic leucodystrophy (arylsulfatase A deficiency), mucopolysaccharidoses (types II, IIIA, IIID and VI are due to sulfatase deficiencies) and X-linked ichtyosis (steroid-sulfatase deficiency). The most classically encountered form begins around the age of 1 or 2 years, but infantile cases appearing at birth have been described. Biological diagnosis is made by evidencing both mucopolysacchariduria and sulfatiduria. Results are confirmed by measuring the activity of several sulfatases in leucocytes. Diagnosis is more difficult to make in fibroblast cultures, as sulfatase residual activities are higher and variable in these cells. The gene SUMF1 is located on chromosome 3p26 and about 20 mutations have been identified. Another homologous SUMF2 gene has been located on chromosome 7q11 and could be responsible for the residual activity found in patients. The only treatment is symptomatic. *Authors: Dr R. Froissart, Dr I. Maire (February 2005)*.
