Mitochondrial protein synthesis and CSA. Heteroplasmic deletions in mitochondrial DNA, which may include mitochondrial tRNA genes, are associated with PMPS. MLASA is associated with mutations in PUS1 and the mitochondrial YARS2. Each of these mutations is expected to lead to defective production of multiple proteins encoded in mitochondrial DNA. Thiamine is involved in multiple mitochondrial pathways, including de novo ribose synthesis and in an enzyme that supplies metabolites to the Krebs cycle, which supplies the heme precursor succinyl-CoA. Therefore, deficiency in the cell-surface high-affinity thiamine transporter SLC19A2, which causes TRMA, might lead to defects both in mitochondrial RNA translation and in heme synthesis.