A case of adult-onset mitochondrial encephalopathy due to m.4296G>A gene abnormality

Abstract

The case is a 30-year-old woman. From the age of 25 years, she had several episodes of cortical blindness and visited a local doctor. Mitochondrial disease was suspected based on findings of cerebral infarction-like imaging and a history of diabetes. However, serum and cerebrospinal fluid lactate levels were normal and no abnormal muscle pathology was found. At the age of 30 years, she visited our hospital with impaired consciousness, cortical blindness, and tremor-like involuntary movements in the neck and right fingers. Brain MRI showed abnormal signals in bilateral basal ganglia, with an increased lactate peak by magnetic resonance spectroscopy and high cerebrospinal fluid lactate levels. Mitochondrial gene analysis identified a m.4296G>A gene mutation. Consequently, we reached a diagnosis of mitochondrial encephalopathy. Adult-onset mitochondrial encephalopathy with m.4296G>A gene mutation is extremely rare. This case showed clinical features caused by damage of both the cerebral cortex and subcortical basal ganglia.