engleski

Arylsulfatase A pseudodeficiency mutations in cerebral palsy

Introduction.Arylsulfatase A (ASA, EC 3.1.6.1) is a lysosomal enzyme involved in sulfatide catabolism. Sulfatides are important lipid constituents of oligodendrocyte membranes, thus contributing to maintenance of myelin sheath integrity. Deficiency of ASA causes metachromatic leukodystrophy, a rare autosomal recessive disorder characterized by the storage of cerebroside sulfate mainly in the nervous tissue. Low ASA activities have been also reported in healthy individuals and several neurological and psychiatric disorders, due to condition termed ASA pseudodeficiency. Two mutations in the ASA gene, responsible for the majority of pseudodeficiency alleles, are designated as N350S and 1524+95 A&#8594; G mutation. Frequency of the mutations associated with ASA pseudodeficiency in the Croatian population has been previously estimated at 6.8 % for N350S and 2.8 % for 1524+95 A&#8594; G mutation. The aim of this preliminary study was to establish the frequency of both described mutations associated with ASA pseudodeficiency in patients with diagnosis of spastic form of cerebral palsy. Materials and Methods. Blood samples were collected from 48 patients with a diagnosis of spastic cerebral palsy. Genomic DNA was extracted from leukocytes and two fragments of ASA gene were amplified using specific primers. After digestion with adequate restriction enzymes, the reaction products were analyzed by electrophoresis on 2-3 % agarose gel. In addition, the activity of arylsulfatase A was determined in leukocyte homogenates by spectrophotometry using p-nitrocatechol sulfate as chromogenic substrate. Results. In analyzed group of patients with diagnosis of cerebral palsy, we found 9 heterozygous carriers of N350S mutation and 8 heterozygous carriers of 1524+95 A&#8594; G mutation. The frequency of mutated alleles was thus estimated at 9.37 % and 8.33 % for N350S and 1524+95 A&#8594; G mutation, respectively. Higher frequency of the 1524+95 A&#61614; G mutation in analyzed group of patients with cerebral palsy was found to be statistically significant in comparison with data obtained for healthy population (P<0.05, chi square-test). Additionally, all subjects detected as heterozygous carriers of either or both analyzed mutations showed slightly lower ASA activity. Interestingly, the majority of patients, which were found to be non-carriers of analyzed mutated alleles, also showed lower ASA activity. Conclusion. Our preliminary results show that the frequency of both mutations responsible for arylsulfatase A pseudodeficiency is higher in patients suffering from spastic cerebral palsy in comparison with healthy population. Also, we suggest that other mutations in the ASA gene probably contribute to lower ASA activity in cerebral palsy.

arylsulfatase A; pseudodeficiency mutations; cerebral palsy

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