Mitochondrial DNA variants in a cohort from Argentina with suspected Leber's hereditary optic neuropathy (LHON)

The present study investigates the spectrum and analysis of mitochondrial DNA (mtDNA) variants associated with Leber hereditary optic neuropathy (LHON) in an Argentinean cohort, analyzing 3 LHON-associated mitochondrial genes. In 32% of the cases, molecular confirmation of the diagnosis could be established, due to the identification of disease-causing variants. A total of 54 variants were observed in a cohort of 100 patients tested with direct sequencing analysis. The frequent causative mutations m.11778G>A in MT-ND4, m.3460G>A in MT-ND1, and m.14484T>C in MT-ND6 were identified in 28% of the cases of our cohort. Secondary mutations in this Argentinean LHON cohort were m.11253T>C p.Ile165Thr in MT-ND4, identified in three patients (3/100, 3%) and m.3395A>G p.Tyr30Cys in MT-ND1, in one of the patients studied (1%). This study shows, for the first time, the analysis of mtDNA variants in patients with a probable diagnosis of LHON in Argentina. Standard molecular methods are an effective first approach in order to achieve genetic diagnosis of the disease, leaving NGS tests for those patients with negative results.

Mitochondrial optic neuropathies: our travels from bench to bedside and back again

The standard scientific method requires that you make an interesting observation, generate a hypothesis and then design an experiment to test the hypothesis. In ophthalmology, as in most fields of medicine, the observations and hypotheses tend to have more degrees of freedom, and the interpretation of experiments is also more complicated and often indeterminate. But sometimes it works out, going back and forth from bench to bedside to bench, in reiterative cycles. A successful example of alternating bench and bedside studies was presented (AAS) at the 2012 Alper Memorial given at the Washington Hospital Medical Center, illustrating a series of questions and investigations that pertain to mitochondrial optic neuropathies, beginning two decades ago, before the concept of mitochondrial optic neuropathies had much meaning. Basic science questions are often best answered by that extraordinary experiment of nature that we call clinical disease, and clinical questions are often best tested in the laboratory.