Ann Lab Med.  2015 Jul;35(4):458-462. 10.3343/alm.2015.35.4.458.

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

• Han M
• Jun SH
• Lee YJ
• Eun BL
• Lee SJ
• Seong MW
• Park SS
• Song SH
• Park HD
• Song J

• KMID: 2045871
• DOI: http://doi.org/10.3343/alm.2015.35.4.458

Abstract

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.

Keyword

Metachromatic leukodystrophy; Arylsulfatase A; Pseudodeficiency; Genetic mutation

MeSH Terms

Cerebroside-Sulfatase
Chromatography, Liquid
DNA
DNA, Complementary
Heterozygote
Leukodystrophy, Metachromatic*
Tandem Mass Spectrometry
Cerebroside-Sulfatase
DNA
DNA, Complementary

Figure

• 

  Fig. 1 Mutational analysis of the novel pathogenic variant of ARSA. (A) Direct sequencing of DNA from the patient (A-a) showing homozygous peaks with a G deletion at the splicing donor site in intron 6 (c.1107+1delG) in contrast to the overlapping peaks due to a heterozygous G deletion in the electropherograms of DNA from the patient's father (A-b) and mother (A-c). (B) Schematic diagram of ARSA with an alternatively spliced region in exon 6 caused by a G deletion in the splicing donor site of intron 6 (c.1107+1delG). (C) Direct sequencing of DNA from the patient (C-a) showing homozygous peaks with a G deletion in exons 6 to 7 in contrast to the overlapping peaks due to a heterozygous deletion in the patient's father (C-b) and mother (C-c).

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