A Case Study-Leber's Hereditary Optic Neuropathy: An Important Cause of Progressive Painless Visual Loss

Leber's Hereditary Optic Neuropathy (LHON) is a maternally transmitted disease of the optic nerve that primarily affects males in their second or third decade. Clinical features include painless acute or subacute loss of vision, deep central scotomas, disc edema, hyperemia and peri-papillary telangiectasia. Patients are otherwise healthy. Mitochondria is a generator of ATP, required for the all the functions of the body. The major types of mutations in this disease are:(1)m.3460G>A (guanine to adenosine); (2)m. 11778G>A (guanine to adenosine); (3)m. 14484T>C (thymidine to cytosine) disrupt key polypeptide subunits of complex I respiratory chain. The final pathological outcome in LHON is apoptotic retinal ganglion cells loss. Objective was to find out the gene mutations in a young male patient with clinical and neurophysiological condition suggestive of LHON, confirmed by genetic testing. A case study was done on 20 year old male patient in neuromedicine OPD in Sri Krishna Hospital, Karamsad after the consent of the patient. Molecular genetic testing for the three common LHON mitochondrial DNA point mutations (targeted mutation analysis) in the patient and his three unaffected sibling sisters were done for confirmation of LHON. Affected male patient on molecular genetic testing revealed mutation on 11778G>A and his three sibling sisters revealed same type of mutation but phenotypically were normal. LHON is a mitochondrial genetic disease characterised by bilateral subacute loss of central vision owing to focal degeneration of the optic nerve. The vast majority of cases are result of one of three mtDNA point mutations. To confirm these mutations molecular genetic testing is now available.