title: Molecular and structural analysis of metachromatic leukodystrophy patients in Indian population.
abstract: Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by mutations in arylsulfatase A (ARSA) gene. No work on molecular genetics of MLD has been reported from India and the mutational spectrum in Indian patients is not known. The present study was undertaken to identify mutations in arylsulfatase A gene in Indian MLD patients, to evaluate genotype-phenotype correlation, and to see the effect of the novel mutants on the protein. Twenty MLD patients (16 families) were screened by ARMS PCR for the most common mutation (c.459+1G>A). Pseudodeficiency alleles were tested by RFLP method whereas rare and novel mutations were scanned by Conformation Sensitive Gel Electrophoresis (CSGE), followed by sequencing. The genotype-phenotype correlation was also attempted. Protein homology modeling analysis was carried out for two novel missense mutations identified, to assess the effect of these mutations on the protein conformation. Nine pathogenic alleles were found in 13 patients (65%). Four previously reported mutations and five novel variants were identified. Five patients (35%) were found to have pseudodeficiency alleles, c.1049A>G (p.Asn350Ser) and c.1524+95A>G. Genotype-phenotype correlation was found to be difficult to establish. Protein modeling studies showed that the mutations cause loss of interactions leading to conformational change in ASA protein. The study identified the mutational spectrum of Indian MLD patients, which will be helpful in genetic counseling, carrier detection and establishing prenatal diagnosis. Homology modeling helped to study conformational change in protein and has implications in generating novel therapeutic molecules.
authors.affiliation: Genetics Division, Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India.
authors.forename: Pallavi
authors.initials: P
authors.lastname: Shukla
authors.forename: Suman
authors.initials: S
authors.lastname: Vasisht
authors.forename: Ranjana
authors.initials: R
authors.lastname: Srivastava
authors.forename: Neerja
authors.initials: N
authors.lastname: Gupta
authors.forename: Manju
authors.initials: M
authors.lastname: Ghosh
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.forename: Raju
authors.initials: R
authors.lastname: Sharma
authors.forename: Arun K
authors.initials: AK
authors.lastname: Gupta
authors.forename: Punit
authors.initials: P
authors.lastname: Kaur
authors.forename: Mahesh
authors.initials: M
authors.lastname: Kamate
authors.forename: Sheffali
authors.initials: S
authors.lastname: Gulati
authors.forename: Veena
authors.initials: V
authors.lastname: Kalra
authors.forename: Shubha
authors.initials: S
authors.lastname: Phadke
authors.forename: Pratibha
authors.initials: P
authors.lastname: Singhi
authors.forename: Alpa J
authors.initials: AJ
authors.lastname: Dherai
authors.forename: Madhulika
authors.initials: M
authors.lastname: Kabra
mesh_terms: D017668:Age of Onset; D000483:Alleles; D001921:Brain / Q000473:pathology; D002553:Cerebroside-Sulfatase / Q000737:chemistry / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D007966:Leukodystrophy, Metachromatic / Q000208:ethnology / Q000235:genetics* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D050505:Mutant Proteins; D002553:Cerebroside-Sulfatase