greatly elevated when the only indication for it is an inborn error of metabolism. in absence of a liver transplant, the msud diet must be adhered to strictly and permanently. however, in both treatment scenarios, with proper management, those affected are able to live healthy, normal lives without experiencing the severe neurological damage associated with the disease. pregnancy control of metabolism is vital during pregnancy of women with msud. to prevent detrimental abnormalities in development of the embryo or fetus, dietary adjustments should be made and plasma amino acid concentrations of the mother should be observed carefully and frequently. amino acid deficiency can be detected through fetal growth, making it essential to monitor development closely. prognosis if left untreated, msud will lead to death due to central neurological function failure and respiratory failure. early detection, diet low in branched-chain amino acids, and close monitoring of blood chemistry can lead to a good prognosis with little or no abnormal developments. average intellectual development is below that of the general population and the severity of the deficit is a related to the time the condition remained undiagnosed and the effectiveness of dietary control including during metabolic crises. epidemiology maple syrup urine disease (msud) is a rare, inherited metabolic disorder. its prevalence in the united states population is approximately 1 newborn out of 180,000 live births. however, in populations where there is a higher frequency of consanguinity, such as the mennonites in pennsylvania or the amish, the frequency of msud is significantly higher at 1 newborn out of 176 live births. in austria, 1 newborn out of 250,000 live births inherits msud. it also is believed to have a higher prevalence in certain populations due in part to the founder effect since msud has a much higher prevalence in children of amish, mennonite, and jewish descent. research directions gene therapy gene therapy to overcome the genetic mutations that cause msud have already been proven safe in animals studies with msud. the gene therapy involves a healthy copy of the gene causing msud is produced and inserted into a viral vector. the adeno-associated virus vector is delivered one time to the patient intravenously. hepatocytes will take up vector and functional copies of the affected gene is msud patients will be expressed. this will allow bcaa to be broken down properly and prevent toxic build up. phenylbutyrate therapy sodium phenylacetate/benzoate or sodium phenylbutyrate has been shown to reduce bcaa in a clinical trial done february 2011. phenylbutyrate treatment reduced the blood concentration of bcaa and their corresponding bcka in certain groups of msud patients and may be a possible adjunctive treatment.