title: A comprehensive survey of mutations in the OPA1 gene in patients with autosomal dominant optic atrophy.
abstract: OBJECTIVE
  To characterize the spectrum of mutations in the OPA1 gene in a large international panel of patients with autosomal dominant optic atrophy (adOA), to improve understanding of the range of functional deficits attributable to sequence variants in this gene, and to assess any genotype-phenotype correlations.
  
  
  METHODS
  All 28 coding exons of OPA1, intron-exon splice sites, 273 bp 5' to exon 1, and two intronic regions with putative function were screened in 94 apparently unrelated white patients of European origin with adOA by single-strand conformational polymorphism (SSCP)-heteroduplex analysis and direct sequencing. Clinical data were collated, and putative mutations were tested for segregation in the respective families by SSCP analysis or direct sequencing and in 100 control chromosomes. Further characterization of selected splice site mutations was performed by RT-PCR of patient leukocyte RNA. Staining of mitochondria in leukocytes of patients and control subjects was undertaken to assess gross differences in morphology and cellular distribution.
  
  
  RESULTS
  Twenty different mutations were detected, of which 14 were novel disease mutations (missense, nonsense, deletion-frameshift, and splice site alterations) and six were known mutations. Mutations were found in 44 (47%) of the 94 families included in the study. Ten new polymorphisms in the OPA1 gene were also identified. Mutations occur throughout the gene, with three clusters emerging: in the mitochondrial leader, in the highly conserved guanosine triphosphate (GTP)-binding domain, and in the -COOH terminus. Examination of leukocyte mitochondria from two unrelated patients with splice site mutations in OPA1 revealed no abnormalities of morphology or cellular distribution when compared with control individuals.
  
  
  CONCLUSIONS
  This study describes 14 novel mutations in the OPA1 gene in patients with adOA, bringing the total number so far reported to 54. It is likely that many cases of adOA are due to mutations outside the coding region of OPA1 or to large-scale rearrangements. Evaluation of the mutation spectrum indicates more than one pathophysiological mechanism for adOA. Preliminary data suggests that phenotype-genotype correlation is complex, implying a role for other genetic modifying or environmental factors. No evidence was found of pathologic changes in leukocyte mitochondria of patients with adOA.
authors.affiliation: Department of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom.
authors.forename: Dawn L
authors.initials: DL
authors.lastname: Thiselton
authors.forename: Christiane
authors.initials: C
authors.lastname: Alexander
authors.forename: Jan-Willem
authors.initials: JW
authors.lastname: Taanman
authors.forename: Simon
authors.initials: S
authors.lastname: Brooks
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenberg
authors.forename: Hans
authors.initials: H
authors.lastname: Eiberg
authors.forename: Sten
authors.initials: S
authors.lastname: Andreasson
authors.forename: Nicole
authors.initials: N
authors.lastname: Van Regemorter
authors.forename: Francis L
authors.initials: FL
authors.lastname: Munier
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Moore
authors.forename: Shomi S
authors.initials: SS
authors.lastname: Bhattacharya
authors.forename: Marcela
authors.initials: M
authors.lastname: Votruba
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D003625:Data Collection; D020558:GTP Phosphohydrolases / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D020180:Heteroduplex Analysis; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D029241:Optic Atrophy, Autosomal Dominant / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D010375:Pedigree; D010641:Phenotype; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D012313:RNA / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012313:RNA; D020558:GTP Phosphohydrolases; C415198:OPA1 protein, human