Background: Maple syrup urine disease (MSUD) is a rare autosomal recessive genetic disorder that is caused by defciency in branched chain ?-ketoacid dehydrogenase complex activity (BCKD). MSUD can be caused by mutation within any of the BCKDHA, BCKDHB, DBT, DLD genes encoding the branched chain ?-ketoacid dehydrogenase complex. BCKD is a mitochondrial complex and is participated in metabolism of branched-chain amino acids (BCAAs) in the energy production pathway. BCKD defects results in accumulation of BCAAs and their ?-ketoacids in the plasma and urine to toxic levels. Patients with MSUD present neurological dysfunction and cognitive impairment such as ketoacidosis, failure to thrive, poor feeding, ataxia, seizure, coma and psychomotor delay. The aim of the present study was to determine the incidence of MSUD in Babol city (Mazandaran province). Method and material: Medical record of patients were investigated in Apr 2007- January 2017. MSUD suspected patients underwent metabolic tests to confrm the disease. All patient came from Babol. Total number of infants during this period of time was obtained from organization of civil registration in Babol. Conclusion: During 10 years, 13 patients were diagnosed. Based on total number of infants in Babol, The incidence of MSUD is estimated to be 1 in 5,795 live births. Some of the patients were the result of consanguineous marriage. In our study, the rate of incidence was much higher than worldwide (1:185000). Our fnding suggests that founder effect may be responsible for the high incidence of MSUD in this population.
