Leber’s hereditary optic neuropathy

Leber’s hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disease caused by several point mutations in mitochondrial DNA. We present the case of a healthy 12-year-old Chinese boy who presented with bilateral, painless, subacute loss of central vision (more severe in the left eye the than right eye) for 1 week. No abnormalities were detected on magnetic resonance imaging of the brain and orbit. Serial Humphrey visual field tests initially showed a centrocaecal scotoma that worsened progressively. Cerebrospinal fluid samples and blood investigations showed normal results. A trial of steroid therapy was commenced with not much improvement in the patient’s vision. A blood sample was then sent for LHON genetic testing and a mitochondrial DNA (mtDNA) G11778A pathogenic mutation was detected. The same mutation was also present in the patient’s mother.