title: Proportion of 11778 mutant mitochondrial DNA and clinical expression in a thai population with leber hereditary optic neuropathy.
abstract: BACKGROUND
  The proportion of mutant mtDNA in blood has been found to correlate with the frequency of visual loss in cases with mtDNA mutations associated with Leber hereditary optic neuropathy (LHON), especially in men. We sought to determine this correlation in a Thai population of LHON.
  
  
  METHODS
  Densitometric quantification of blood mtDNA with the 11,778 LHON mutation in 137 symptomatic cases and their asymptomatic maternal relatives in 30 Asian pedigree families was performed. Asymptomatic maternal relatives under the age of 16 years were excluded. The visual outcome in symptomatic cases with homoplasmy and heteroplasmy was compared.
  
  
  RESULTS
  Heteroplasmy was detected in eight (12.9%) symptomatic and 30 (40%) asymptomatic individuals. The quantification of blood mutant mtDNA in the eight symptomatic cases ranged from 44% to 93% (mean=75%). The visual outcome of the cases with heteroplasmy was not different from that of cases with homoplasmy. There was a correlation between the proportion of mutant mtDNA and the likelihood of visual loss.
  
  
  CONCLUSIONS
  The prevalence of heteroplasmy among pedigrees of the 11,778 LHON mutation in Thailand was similar to that of other Asian populations and may be greater than in 11,778 LHON pedigrees from white backgrounds. The proportion of mutated mtDNA correlated with visual loss, but the effect of heteroplasmy on clinical expression seemed not to relate to gender.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. siwck@mahidol.ac.th
authors.forename: Wanicha L
authors.initials: WL
authors.lastname: Chuenkongkaew
authors.forename: Rungnapa
authors.initials: R
authors.lastname: Suphavilai
authors.forename: Lookjan
authors.initials: L
authors.lastname: Vaeusorn
authors.forename: Nopasak
authors.initials: N
authors.lastname: Phasukkijwatana
authors.forename: Patcharee
authors.initials: P
authors.lastname: Lertrit
authors.forename: Bhoom
authors.initials: B
authors.lastname: Suktitipat
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000369:Aged, 80 and over; D002648:Child; D004272:DNA, Mitochondrial / Q000097:blood / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029242:Optic Atrophy, Hereditary, Leber / Q000453:epidemiology / Q000235:genetics*; D010375:Pedigree; D017354:Point Mutation; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D013785:Thailand / Q000453:epidemiology; D014792:Visual Acuity
chemical_list: D004272:DNA, Mitochondrial