Second trimester prenatal diagnosis of Sanfilippo syndrome type C

Sanfilippo syndromes or mucopolysaccharidosis type III are inherited disorders that result from a deficiency in one of the four following lysosomal enzymes involved in the degradation of heparan sulphate: heparan sulphate sulphamidase (type A); N-acetyl-α-D-glucosaminidase (type B); acetyl-CoA: α-glucosaminide N-acetyltransferase (type C); and N-acetylglucosamine-6-sulphate sulphatase (type D). Patients excrete heparan sulphate in urine in excessive amounts. Discrimination between the four subtypes requires activity determination of the enzymes involved since clinical and radiological symptoms are very similar (Maire 1991)