MARS2 and Leukoencephalopathy: Complex rearrangements in MARS2 (mitochondrial methionyl-tRNA synthetase) were described in a cohort of patients with autosomal recessive spastic ataxia with leukoencephalopathy, whereas mutations in FARS2 (MIM# 611592) (Phenylalanyl-tRNA synthetase) were identified in three patients with fatal epileptic mitochondrial encephalopathy, consistent with Alpers’ syndrome.