Identification of the variants in PARL, the nuclear modifier gene, responsible for the expression of LHON patients in Thailand.

The present study explored variation in the PARL gene as one of the potential nuclear modifiers in the pathogenesis of Leber hereditary optic neuropathy (LHON). Ten exons, their franking introns and 3' UTR of the PARL gene were analysed. Seventeen SNPs detected were investigated in 83 affected and 53 unaffected individuals from 47 independent Thai LHON pedigrees using MQLS statistics in order to minimize the influence of the family background. Three intronic SNPs (rs953419, rs3749446 and rs1402000) showed statistically significant results. Joint haplotypes were constructed based on the genotypes at 3 SNPs and 7 possible haplotypes were observed in the 136 subjects. Our findings that the frequency of the haplotype AAC, and AAT were significantly higher in the unaffected cases and the frequencies of haplotype GGT were significantly higher in LHON cases, indicate that it might have a role in the penetrance of this mitochondrial disease.