ABSTRACT
Objective@#To detect pathogenic variant of ARSA gene in an infant with late infantile metachromatic leukodystrophy (MLD).@*Methods@#The male proband had an onset of walking dysfunction and seizure at 28 months. Arylsulfatase A activity of his peripheral blood leucocytes was 26.9 nmol/mg.17h, and cranial MRI showed wild symmetrical demyelination. With genomic DNA extracted from his peripheral blood sample, all coding exons and splicing sites of the ARSA gene were subjected to Sanger sequencing. PubMed Protein BLAST system was employed to analyze cross-species conservation of the mutant amino acid. Ucsf chimera software was used to analyze the impact of candidate variants on the secondary structure of the protein product. Impact of potential variants was also analyzed with software including PolyPhen-2, Mutation Taster, SIFT and PROVEAN. Whole-exome sequencing was carried out to identify additional variants which may explain the patient’s condition.@*Results@#The proband was found to harbor compound heterozygous variants of the ARSA gene [c.467G>A (p.Gly156Asp) and c. 960G>A (p.Trp320*)], neither of which was reported previously. As predicted by Ucsf chimera software, the c. 960G>A (p.Trp320*) variant may demolish important secondary structures including α-helix, β-strand and coil of the ARSA protein, causing serious damage to its structure and loss of function. The c. 467G>A (p.Gly156Asp) variant was predicted to be "probably damaging" by PolyPhen-2, Mutation Taster and SIFT software.@*Conclusion@#The patient’s condition may be attributed to the compound heterozygous c. 467G>A (p.Gly156Asp) and c. 960G>A (p.Trp320*) variants of the ARSA gene. Above results have facilitated genetic counseling and prenatal diagnosis for this family.
ABSTRACT
Metachromatic leukodystrophy is an inherited lysosomal disorder caused by autosomal reces-sive mutations of ARSA gene or PASP gene,which result in the accumulation of sulfatides in the central and pe-ripheral nervous system leading to demyelination. The disease is classified into a late-infantile,juvenile and adult onset type based on the age of onset,all characterized by a variety of neurological symptoms,which eventually lead to death if untreated. There is no curative treatment for all types and stages. This review discusses pathogen-esis,clinical manifestations,diagnostic process and efficacy of current and possible future therapies such as en-zyme replacement therapy,hematopoietic stem cell transplantation and gene therapy. A longer follow up period for the above therapies are needed to come to a general conclusion and improve treatment options for metachro-matic leukodystrophy.
ABSTRACT
Abstract Metachromatic leukodystrophy disorder (MLD) is an autosomal recessive and lysosomal storage disease. The disease is caused by the deficiency of the enzyme arylsulfatase A (ARSA) which is encoded by the ARSA gene. Different mutations have been reported in different populations. The present study was aimed to detect the mutation type of the ARSA gene in three relative Iranian patients. We found a novel homozygous missense mutation c.1070 G > T (p.Gly357Val) in exon 6 of these patients. The mutation was found to be reported for the first time in MLD patients. The data can update the mutation profile and contribute toward improved clinical management and counseling of MLD patients.
ABSTRACT
Metachromatic leukodystrophy (MLD) is the rare neurometabolic disease caused by the deficiency of the enzyme arylsulfatase A resulting in a deficiency of sulfatide degradation and the target gene is ARSA gene. We report a case of the late infantile form of MLD that was confirmed by means of enzyme assay and gene analysis with typical brain MRI and MR spectroscopy finding.