BACKGROUND AND OBJECTIVE: Maple syrup urine disease is a rare inborn metabolic inherited disorder caused by deficiency of branched chain α-keto acid dehydrogenase complex and leading to accumulation of branched chain amino acids in body fluid. The incidence of MSUD is higher in populations with high consanguineous marriage. BCKD is a mitochondrial complex which is encoded by four nuclear genes (BCKDHA, BCKDHB, DBT, and DLD) and MSUD can be caused by mutation within any of these four genes. Accumulation of metabolic is associated with impairment of energy metabolism, provoke apoptosis, dysfunctional neurotransmitter synthesis and neuropathological defects such as seizure, psychomotor delay and coma. In the present study, we investigated the incidence of MSUD in Iran, compiled previously reported mutations in Iranian population and also explained molecular pathomechanisms underlying MSUD. METHODS: To compile MSUD mutations, we systematically reviewed PubMed and magiran databases to find related articles in English and Persian language, respectively. The key words "MSUD" and "Iran" was used as query. FINDINGS: Until 9th December 2018, twenty four MSUD mutations were collected from Iranian population of which 18 mutations have been only identified in Iran and were not reported in other populations yet. Likewise, because of high consanguineous marriages, the incidence of MSUD were higher than worldwide average in different provinces. CONCLUSION: Identification and compiling of MSUD mutations in Iranian population can be useful for prenatal genetic diagnosis in at risk families and play crucial role in early diagnosis and also treatment before starting neurological symptoms in newborns.
