Fumarate hydratase deficiency (FHD) caused by biallelic alterations of the FH, by the hereditary mode of autosomal recessive, is a rare disorder of the tricarboxylic acid cycle, classically characterized by encephalopathy, profound psychomotor retardation, seizures, a spectrum of brain abnormalities and early death in childhood. The gene discussed is FH; the disease is fumaric aciduria.