Biochemical and Genetic Analysis of Seven Korean Individuals With Suspected Metachromatic Leukodystrophy

Metachromatic leukodystrophy (MLD) is an autosomal recessive disease caused by a deficiency in arylsulfatase A (ARSA). However, decreased ARSA activity is also observed in pseudodeficiency (PD). To distinguish between MLD and PD, we performed gene mutation and sulfatide analyses by using dried blood spots (DBSs) from seven Korean individuals who underwent an analysis of ARSA activity. DNA was extracted from DBSs, and PCR-direct sequencing of ARSA was performed. The cDNA obtained was analyzed to confirm a novel mutation. Of the seven subjects, three were confirmed as having MLD, one was confirmed as having MLD-PD, one was confirmed as having PD, and the remaining two were obligate heterozygotes. We verified the novel pathogenic variant c.1107+1delG by performing familial and cDNA analyses. Sulfatide concentrations in DBSs were analyzed and were quantified by using ultra-performance liquid chromatography and tandem mass spectrometry, respectively. Total sulfatide concentration was inversely correlated with ARSA activity (Spearman's coefficient of rank correlation, P=0.929, P=0.0025). The results of this mutational and biochemical study on MLD will increase our understanding of the genetic characteristics of MLD in Koreans.