Leigh syndrome should be differentiated from other diseases associated with degeneration of the basal ganglia in the paediatric population, such as carbon monoxide intoxication, infantile bilateral striatal necrosis (IBSN), Wilson’s disease, juvenile Huntington’s chorea, neurogeneration with brain iron accumulation, familial degeneration of the striatum and GAMT (guanidinoacetate methyltransferase) deficiency. The gene discussed is GAMT; the disease is infantile bilateral striatal necrosis.