Effect of environmental factors on Leber hereditary optic neuropathy

Leber hereditary optic neuropathy (LHON) is a maternally inherited disorder associated with mitochondrial DNA (mtDNA) mutations. In the LHON families in different ethnic backgrounds, the mutations of ND1 G3460A, ND4 G11778A and/or ND6 T14484C in the genes encoding subunits of respiratory chain complex I account for more than 50%. But, as we know, the phenotypes of mitochondrial diseases are varied, so the same mutational points may generate different clinical phenotypes, and conversely, different mtDNA mutation variants may generate the similar phenotypes. Some states of LHON including the prone to male, incomplete penetrance, and phenotypic variability of vision loss suggest that other modifier factors probably play a synergic role in the development of LHON. Environmental factor, such as chronic cyanide poisoning, smoking, drinking, trauma, nutrition deficiency and mtDNA methylation, affects mitochondrial function. Therefore, there is an inheritance of gene and environment interactions affecting LHON.