SLC25A1 and Encephalopathy: In addition, homozygous mutations in SLC25A1, encoding a mitochondrial citrate carrier, cause combined D-2- and L-2-hydroxyglutaric aciduria, severe neonatal epileptic encephalopathy, absence of developmental progress, and often early death [91], and mutations in SLC25A19, encoding a mitochondrial transporter of a TCA cycle cofactor (thiamine pyrophosphate), cause encephalopathy and progressive polyneuropathy [92].