Lhlon Research Paper

Leber hereditary optic neuropathy, also known as LHON, is a neurodegenerative mitochondrial disease that leads to blindness. LHON is an inherited form of vision loss that usually appears in a person’s teens and in rare cases appears in early childhood or in adult years (Leber hereditary optic neuropathy - Genetics Home Reference). The Initial symptoms of LHON are usually blurring and clouding of vision. The symptoms of LHON can start in one eye or both at the same time. Once symptoms start in one eye the other eye will be symptomatic after a few weeks to a few months. LHON usually affects the sufferer’s central vision, which affects the ability to read, drive, or recognize faces. The vision loss results from the death of cells in the optic nerve. The vision loss is
usually permanent, but in some cases can gradually get better. Vision loss is usually the only symptom in LHON; however, there have been some cases with symptoms such as movement disorders, tremors, and cardiac conduction defects. Mutations in the MT-ND1, MT-ND4, MT-ND4L, or MT-ND6 gene can cause LHON (Gene Therapy May Help Leber's Hereditary Optic Neuropathy Patients). These are genes that are found in the mitochondria.
Males are affected more than females; furthermore, LHON affects 1 in 50,000 people in northeast Finland and England. Approximately 100 Americans are diagnosed with LHON each year joining the 4000 Americans who already suffer from this genetic mutation. The most common LHON mutation is the “11778 mutation.” A woman that carries the LHON mutation will pass it to her children; although, men with this mutation never pass it to their children ("About LHON"). Scientists are now trying to treat this mitochondrial disease with gene therapy. Gene therapy is designed to correct the damaged mitochondrial DNA. The therapy has to be delivered to the mitochondria in each cell, which can be very challenging. Researchers constructed a nuclear version of the mitochondrial ND4 gene and tested the safety and efficiency of recombinant AAV2-ND4 in patients that carried the G11778A mutation for LHON. They injected rAAV2-ND4 in one eye of nine patients (Scientists test new gene therapy for vision loss from a mitochondrial disease, 2015). The patients were followed for nine months. The visual acuity and visual field were measured to determine the treatment’s
effectiveness. The researchers also preformed physical examinations. Researchers observed notable improvement in visual acuity in the eyes of the six patients injected with rAAV2-ND4 after nine months of follow up appointments (Gene Therapy May Rescue Visual Acuity in People with LHON Disease, 2016). Researchers hypothesized the improvement of the visual acuity was due to the fact that the normal ND4 gene was being supplied to the mitochondria, which would result in an increased energy supply to the optic nerve. These results are believed to suggest that the rAAV2-ND4 injection is a safe and clever strategy for treating LHON patients ("Gene Therapy May Rescue Visual Acuity in People with LHON Disease", 2016).