Reduced frequency of known mutations in a cohort of LHON patients from India.
BACKGROUND
Three mitochondrial mutations account for 95% of Leber's hereditary optic neuropathy (LHON) in the European population: G3640A, G11778A and T14484C. The purpose of the study was to investigate the frequency of these mitochondrial DNA mutations in LHON patients from a South Indian population.


METHODS
LHON was diagnosed by inheritance pattern, ophthalmologic examination, and by exclusion of non-LHON forms of optic neuropathy. Ninety unrelated LHON patients and 20 at-risk family members (5 with LHON and 15 without LHON) underwent molecular screening for the mitochondrial DNA mutations G3640A, G11778A and T14484C by amplification refractory mutation system (ARMS) polymerase chain reaction (PCR). Positive results were confirmed with bi-directional sequencing.


RESULTS
The G11778A mutation was detected in 8 of 90 (8.9%) LHON families. The T14484 mutation was detected in 3 of 90 (3.3%) LHON families. No instances of the G3460A mutation were detected. Other variants were incidentally detected by the DNA sequencing assay.


CONCLUSIONS
Three mitochondrial mutations (G3640A, G11778A and T14484C) account for the vast majority of LHON cases in Europe. However, these mutations were detected in only 11 (12%) of 90 LHON families from Southern India in our study. These results suggest that a different set of LHON-causing mutations is present in the South Indian population than in the European population. Further study of subjects with LHON from India may lead to the discovery of novel disease-causing mutations and/or genes.
Sundaresan
Periasamy
P
Department of Genetics, Dr. G. Venkataswamy Eye Research Institute, Aravind Medical Research Foundation, Madurai, Tamilnadu, India.
Kumar
S Mahesh
SM
Thompson
Stewart
S
Fingert
John H
JH
D000328:Adult; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D006801:Humans; D007194:India; D008297:Male; D028361:Mitochondrial Diseases / Q000235:genetics*; D009154:Mutation; D029242:Optic Atrophy, Hereditary, Leber / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D055815:Young Adult
D004272:DNA, Mitochondrial