title: SCA 1, SCA 2 & SCA 3/MJD mutations in ataxia syndromes in southern India.
abstract: OBJECTIVE
  Spinocerebellar ataxias (SCAs) are often caused by expansions of CTG/ CAG trinucleotide repeat in the genome. Expansions at the SCA1, 2 and 3 loci are the most frequent, but differences in their relative proportion in regions occur across the world. We carried out this study to assess the occurrence of SCA1, 2 and 3, at a tertiary neuro-psychiatric center in Bangalore, Karnataka.
  
  
  METHODS
  Probands (N=318) who were diagnosed to have an ataxia syndrome (progressive degenerative ataxia of unknown cause) attending the clinical services of the National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore, were evaluated over a period of three years. Standard protocols were used for both clinical and molecular diagnosis.
  
  
  RESULTS
  Genotyping established that SCA1, 2 and 3 accounted for more than one third of the ataxia cases seen in the clinic. In the cases with established family history and autosomal dominant inheritance SCA1 was most prevalent followed by SCA2 and SCA3.
  
  
  CONCLUSIONS
  Our findings suggested SCA1 rather than SCA2 to be the more common mutation in southern India. Large numbers of SCA3 probands were also identified. Differences in prevalence of these syndromes within India need to be explored further for founder effects, correlations with phenotype, and patterns of outcome. Family history was not apparent in almost a fifth of those tested positive, highlighting the value of testing even in the absence of family history. Molecular testing should be extended to cover the other forms of ataxia, of which a large number are now known. Combined efforts to confirm the presence of these less common forms, as well as family studies to detect novel mutations, are necessary in this context in India.
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neuro Sciences, Bangalore, India.
authors.forename: Nithin
authors.initials: N
authors.lastname: Krishna
authors.forename: Surendra
authors.initials: S
authors.lastname: Mohan
authors.forename: B S
authors.initials: BS
authors.lastname: Yashavantha
authors.forename: A
authors.initials: A
authors.lastname: Rammurthy
authors.forename: H B
authors.initials: HB
authors.lastname: Kiran Kumar
authors.forename: Uma
authors.initials: U
authors.lastname: Mittal
authors.forename: Shivani
authors.initials: S
authors.lastname: Tyagi
authors.forename: Mitali
authors.initials: M
authors.lastname: Mukerji
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Jain
authors.forename: Pramod Kumar
authors.initials: PK
authors.lastname: Pal
authors.forename: Meera
authors.initials: M
authors.lastname: Purushottam
mesh_terms: D000293:Adolescent; D000328:Adult; D000067696:Ataxin-1; D000067699:Ataxin-3; D000067528:Ataxins; D005260:Female; D005838:Genotype; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D020754:Spinocerebellar Ataxias / Q000235:genetics*; D013577:Syndrome
chemical_list: C000593749:ATXN1 protein, human; D000067696:Ataxin-1; D000067528:Ataxins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; C092341:ATXN3 protein, human; D000067699:Ataxin-3