Increased prevalence of pervasive developmental disorders in children with slight arylsulfatase A deficiency.

Arylsulfatase A deficiency (less than 15% of controls) is responsible for a neurological disorder known as metachromatic leukodystrophy. Nonetheless, low levels of the enzyme (15-50% of controls, higher than in metachromatic leukodystrophy) in adult patients have been related to neuropsychiatric disorders. On the other hand, there are only few and controversial data on the significance of reduced arylsulfatase A activity in children. This led us to perform the present study. Various classes of arylsulfatase A activity in children have been related with different groups of neuropsychiatric disorders and compared with a similar number of healthy children. We found a high percentage of reduced arylsulfatase A (less than 50% of controls) in children with pervasive developmental disorders (10.25%). Unexpectedly, raising the threshold level for considering arylsulfatase A deficiency up to 70% of controls resulted in a marked increase in the incidence of pervasive developmental disorders. This new class, arylsulfatase A slight deficiency, contained the highest number of patients affected by psychiatric symptoms. This suggests that arylsulfatase A slight deficiency could be a marker of a subclass of pervasive developmental disorders.