FREQUENCY OF THE ARYLSULFATASE-A PSEUDODEFICIENCY ALLELE IN THE SPANISH POPULATION

Pseudodeficiency in arylsulphatase A (ASA) is a relatively frequent co ndition in healthy individuals. It produces a reduction in enzyme acti vity similar to that found in metachromatic leukodystrophy (MLD). Unam biguous discrimination between the two conditions cannot be achieved t hrough conventional enzyme activity assays. A PCR method has been deve loped which detects the pseudodeficiency (pd) allele using a single pa ir of primers encompassing the mutation site and hair follicles as the source of DNA. The frequency of this allele in the Spanish population has been evaluated and correlations between different genotypes and A SA activity levels have been established. Ten out of 55 individuals we re heterozygous for the ASA pd allele, while two were homozygous. The allele frequency was thus 12.7%.