Systematic gene hunting for nuclear modifiers in Leber’s hereditary optic neuropathy and their validation in model systems

Leber's hereditary optic neuropathy (LHON) is a blinding disorder affecting prevalently young males, characterized by the selective degeneration of only a specific subtype of cells in the retina, the retinal ganglion cells. LHON is due to a genetic defect in proteins involved in mitochondrial function. Mitochondria are small organelles residing within the cell, which are the major energy producers for cell life; they also produce poisoning compounds, as the reactive oxygen species, which are dangerous and may induce cell death (apoptosis). Despite the main genetic defect is located in the mitochondrial DNA (mtDNA), a small circular molecule of nucleic acid residing within the mitochondria, it is still unknown why not all the individuals carrying the mtDNA mutations become affected. Thus, the presence of the mtDNA genetic defect is necessary but not sufficient to cause optic neuropathy and it is assumed that additional factors are modulating the risk of visual loss. This current project is focused on the identification of the nuclear genes who may contribute to the development of the optic neuropathy. To this aim, we will use different genetic approaches on samples collected in our previous Telethon grant and the results will be validated in model systems consisting of cell lines from patients and a newly developed mtDNA mutant fly model. We strongly believe that the full comprehension of the genetic complex mechanisms regulating the disease expression in LHON will greatly help patients and will provide tools for a therapy.