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Molecular genetics of metachromatic leukodystrophy
V Gieselmann1, J Zlotogora, A Harris
1Institut für Biochemie II, Georg-August-Universität Göttingen, Germany.
Human Mutation
|January 1, 1994
Summary
Metachromatic leukodystrophy (MLD) is a genetic disorder causing progressive demyelination due to impaired cerebroside sulfate degradation. Mutations in the arylsulfatase A gene are common, but distinguishing MLD from asymptomatic arylsulfatase A deficiency is crucial for diagnosis.
Area of Science:
- Neuroscience
- Genetics
- Biochemistry
Background:
- Metachromatic leukodystrophy (MLD) is an inherited lysosomal storage disease.
- It results from mutations in the arylsulfatase A (ARSA) or prosaposin (PSAP) genes.
- These mutations impair the degradation of cerebroside sulfate, leading to myelin sheath destruction.
Purpose of the Study:
- To investigate the genetic basis of MLD.
- To characterize mutations in ARSA and PSAP genes.
- To differentiate MLD from asymptomatic ARSA deficiency.
Main Methods:
- Genetic analysis of patients with MLD.
- Identification and characterization of mutations in ARSA and PSAP genes.
- Correlation of genotype with phenotype severity.
Main Results:
- Mutations in the ARSA gene are more frequent than in the PSAP gene.
- 31 amino acid substitutions, 1 nonsense mutation, 3 deletions, and 4 splice site mutations identified in ARSA.
- Two ARSA mutant alleles are common, while others are rare and heterogeneous.
- Amino acid substitutions in ARSA cluster in exons 2 and 3.
- Phenotypic variability observed even in patients with identical genotypes.
- Asymptomatic ARSA deficiency is common in the general population and must be differentiated from MLD.
- Six patients with PSAP gene mutations described, with 3 identified defective alleles.
Conclusions:
- MLD is primarily caused by ARSA gene mutations, with PSAP mutations being rare.
- Genetic analysis is essential for diagnosing MLD and distinguishing it from asymptomatic ARSA deficiency.
- Understanding genotype-phenotype correlations is important for genetic counseling, despite observed variability.