Zhou X et al. – The data convincingly show that the ND1 T3866C mutation leads to Leber's hereditary optic neuropathy (LHON). This mutation may be insufficient to produce a clinical phenotype. Other modifier factors may contribute to the phenotypic manifestation of the T3866C mutation. The T3866C mutation should be added to the list of inherited factors for molecular diagnosis of LHON. Thus, the authors' findings may provide new insights into the understanding of pathophysiology and valuable information on the management of LHON.