Arylsulfatases isoenzymes in metachromatic leucodystrophy/detection of a new variant by electrophoresis improvement of quantitative assay.

Arylsulfatase A and B activities were assayed in leucocytes of 43 controls, 11 cases of Metachromatic Leucodystrophy and 7 parents or siblings of patients, using a new technique implying specific inhibitors for leucocyte enzymes. Heterozygotes can be determined, with a 50% value compared to the control, in variant B. Electrophoresis of leucocytes after enzymatic staining for arylsulfatase, is a complementary technique which allowed the detection of a new form of metachromatic leucodystrophy.