Two siblings with metachromatic leukodystrophy caused by a novel identified homozygous mutation in the ARSA gene.

ABSTRACT

Background Metachromatic leukodystrophy (MLD) is an autosomal recessively (AR) inherited disease caused by the deficiency of the enzyme arylsulfatase A (ARSA). Although MLD is the most common form of hereditary leukoencephalopathy, it is still very rare. More than 200 gene mutations have been identified in the ARSA gene. The most frequently identified mutation is the one located on chromosome 22q13.33. In the present study, new mutations are reported in two siblings of different ages and with different clinical presentations. Case presentation A 9-year-old male patient, suffering from ataxia, attention deficit and perceptual difficulties, was first seen at the age of 7. While the findings of neurological examination and neuroradiological evaluation suggested MLD, the ARSA enzyme levels were analyzed and found to be at a lower limit. Genetic analysis revealed variant homozygous mutations of the ARSA gene at p.N352S/c.1055T>C in exon 6 and at p.E331K/c.991G>A in exon 7. In the genetic analysis of his three siblings and parents, a variant heterozygous mutation of the ARSA gene was detected at p.N352S/c.1055T>C in exon 6 and at p.E331K/c.991G>A in exon 7. Conclusions MLD is a rare disease; however, it is likely to find different variant forms in our population, in which the frequency of consanguineous marriages is high. Genetic diagnosis is important in symptomatic cases with enzyme levels within the normal ranges.