Diagnosis of Leber?s hereditary optic neuropathy (LHON)
analysis of MT-ND1, MT-ND4 and MT-ND6 in patients with LHON
Leber´s hereditary optic neuropathy (LHON), a disease affecting vision, is caused by several point mutations in mitochondrial DNA. Mutations leading to a defect NADH ubiquinone oxidoreductase protein will affect the respiratory chain and cause a disturbed ATP production. It is still unknown why this defect leads to the degeneration of retinal ganglion cells and cells in the opticus nerve as well as demyelination of axons in these areas. Analysis of mitochondrial DNA is an important tool in the diagnosis of the disease. At the present time analysis is based on cleavage by restriction enzymes, which only detects two of the most frequent mutations: m.3460G>A and m.11778G>A. This is far too few considering that more than 30 mutations are known to be associated with LHON. Therefore a new analysis method is requested. Here we describe a method based on the sequencing of the mitochondrial genes MT-ND1, MT-ND4 and MT-ND6, which will detect more than 15 different point mutations associated with the disease. To validate the analysis, DNA from 31 patients with LHON symptoms were sequenced; of these 10 were found to be positive for a LHON mutation. This result indicates that the sequencing analysis will be more effective in diagnosis of LHON than restriction enzymes.