Multiple sulfatase deficiency
Multiple sulfatase deficiency (also known as "Austin disease," and "Mucosulfatidosis") is a very rare autosomal recessive lysosomal storage disease caused by a deficiency in multiple sulfatase enzymes, or in formylglycine-generating enzyme, which activates sulfatases. It is similar to mucopolysaccharidosis.
Symptoms of this disorder commonly appear between one and two years of age. Symptoms include mildly coarsened facial features, deafness, ichthyosis and an enlarged liver and spleen (hepatosplenomegaly). Abnormalities of the skeleton, such as a curving of the spine and breast bone may occur. The skin of individuals afflicted with this disorder, is typically dry. Children affected by this disorder develop more slowly than normal and may display delayed speech and walking skills.
Multiple sulfatase deficiency is thought to be caused by any mutation of the SUMF1 gene which would render its protein product, the formylglycine-generating enzyme (FGE), defective. These mutations result in inactive forms of FGE. This enzyme is required for posttranslational modification of a cysteine residue in the sulfatase enzyme active site into formylglycine, which is required for its proper function.
The diagnosis of this disorder relies on the detection of mucopolysaccharides as well as other sulfated complex sugars in the individual's urine; certain specific changes on brain MRI scans may also lead to the diagnosis. A definite diagnosis is made by the demonstration of a deficiency of more than a single sulfatase in either white blood cells, obtained through a blood test or cultured fibroblasts from a skin biopsy, or by genetic analysis of the SUMF1 gene.
At the present time, there is no cure for children affected by MSD, but there are many ways of helping children to enjoy their lives and to manage the problems they will face. It may be that treatment will be available in the future.