Diagnosis of classical Morquio's disease:N‐acetylgalactosamine 6‐sulphate sulphatase activity in cultured fibroblasts, leukocytes, amniotic cells and chorionic villi

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Abstract
The tritiated disulphated trisaccharide 6-sulpho-N-acetylgalactosamine-glucuronic acid-6-sulpho-N-acetyl[1-3H]galactosaminitol was prepared from chondroitin 6-sulphate for use as a substrate forN-acetylgalactosamine 6-sulphate sulphatase. The reaction product was separated on ECTEOLA cellulose rather than Dowex 1×2. The mean activities of normal fibroblasts, leukocytes and amniotic cells were 8.43, 2.59 and 3.14 nmol h−1 mg protein−1, respectively. Fibroblasts from five patients with classical Morquio's disease (mucopolysaccharidosis IVA; MPSIVA) and one patient with neonatal multiple sulphatase deficiency displayed activities of less than 5% of control mean. Activity in amniotic cells from a pregnancy where the fetus was affected with MPS IVA was 6% of control mean. Activity was also found to be present in normal specimens of chorionic villi (mean value 1.21 nmol h−1 mg protein−1), demonstrating the feasibility of first trimester prenatal diagnosis of MPS IVA by assay of activity in this tissue.