An Italian Cohort Study Identifies Four New Pathologic Mutations in the ARSA Gene

Metachromatic leukodystrophy is an autosomal recessive neurodegenerative disorder of the myelin metabolism due to the impaired function of the lysosomal enzyme arylsulfatase A. Three major clinical variants of metachromatic leukodystrophy (MLD) have been described: late infantile, juvenile, and late onset. The infantile form, whose clinical onset is usually before the age of 2 years, is the most frequent. The juvenile form manifests itself between 3 and 16 years and the late-onset form manifests at any time after puberty. As of today, more than 150 mutations causing MLD have been identified in the ARSA gene that encodes arylsulfatase A. In this paper, we report our experience with the diagnosis of MLD in seven Italian patients from unrelated families. We found 11 different mutations, four of which have not been previously described: c.1215_1223del9 (p.406_408del), c.601 T>C (p.Tyr201His), c.655 T>A (p.Phe219Ile), and c.87C>A (p.Asp29Glu). Our data show once more that there are still several mutations to be discovered in the ARSA gene and there are rarely repeating ones found in the population. The predictive value of the enzyme activity tests in regard to clinical manifestations is extremely limited.