![]() ![]() ![]() The mutation proved to be a single nucleotide substitution (G to A) in a splice donor site. dbt is predicted to be 493 amino acids and is ∼78% identical to its human counterpart. Using genomic databases and by sequencing nearby genes, the identity of que was found to be dihydrolipoamide branched-chain transacylase E2 ( dbt), which encodes a component of the BCKD complex. ![]() To further elucidate the genomic location, single nucleotide polymorphism (SNP) markers were used to determine a specific 0.36 cM interval. First, using positional cloning, it was found that que is located on chromosome 22. Research was then performed to uncover the genetic defect in que mutants. MSUD has an autosomal recessive inheritance pattern and affects approximately one in 185,000 people worldwide, with certain communities having a higher incidence of the disease ( Skvorak, 2009). The CNS is disrupted by the elevated levels of BCAAs and α-keto acids, resulting in dysmyelination, cerebral edema, dystonia, coma, retardation, psychiatric problems and even death within weeks of birth ( Friedrich et al., 2012). The abnormal odor of secretions is among the milder symptoms of the disease. Eliminating the proper function of the BCKD complex results in an accumulation of α-keto acids and BCAAs in plasma and tissues ( Friedrich et al., 2012), resulting in MSUD, which is named after the odor of bodily secretions of those affected by this disease. The BCKD complex responsible for this reaction is composed of three catalytic subunits encoded by four genes ( Friedrich et al., 2012). Next, α-keto acids undergo oxidative decarboxylation through the actions of the mitochondrial branched-chain α-keto acid dehydrogenase (BCKD) complex. The amino acids leucine, isoleucine and valine are first converted to α-keto acids through a transamination reaction. It is important to let your obstetrician know that you have a child with MSUD if you are planning future pregnancies so that they can discuss testing options with you and prepare accordingly.Maple syrup urine disease (MSUD) is a rare inherited central nervous system (CNS) disorder involving defects in the metabolism of branched-chain amino acids. Your metabolic doctor and/or pediatrician will advise you about whether siblings should be tested for MSUD. Children from the same father and mother as the affected infant have a 1 in 4 (25%) chance of having the same condition. WHAT ABOUT MY OTHER CHILDREN/FUTURE CHILDREN? A metabolic nutritionist will teach you how to follow the diet and prepare the formula as well as provide assistance in obtaining the formula through your health care provider or state agency.Ħ. Frequent monitoring of blood amino acid levels is required so the diet prescription can be adjusted as needed. A special medical formula and strict low protein diet will be prescribed by your doctor. WHAT IS THE TREATMENT? DOES IT WORK? IS THE DIET DIFFICULT TO DO/EXPENSIVE? It is important to be vigilant and consider every illness seriously.ĥ. Special care must be taken during times of illness as the body will break down its own protein which can raise the level of leucine in the blood to dangerous levels. However, children with MSUD are at risk for intellectual and developmental disabilities. With proper care your child will be able to live a relatively normal and productive life. Blood levels will be monitored and the diet adjusted throughout the lifespan, although most frequently during the early years. If your baby has MSUD, he or she will have to be on a special protein restricted diet, and also take a special formula to ensure that the diet is adequate and balanced. Being a carrier does not affect a person at all. Each of you will have one mutated gene (a carrier). This means that if your baby has MSUD, he/she has two abnormal genes, one from the mother and one from the father. MSUD is an autosomal recessive genetic disorder. ![]() The presence of alloisoleucine or genetic testing can also determine whether your baby has MSUD. The newborn screening test will be repeated and additional tests will be undertaken to help determine whether or not your baby has MSUD. If your baby’s newborn screening result showed a higher than normal leucine level, your child may have MSUD. HOW AND WHEN WILL WE KNOW IF MY BABY HAS MSUD? The inability to completely metabolize these amino acids leads to a toxic build up of these and related acids in the body. MSUD, also known as Maple Syrup Urine Disease, is an Inborn Error of Metabolism caused by a defect in the enzyme needed to break down a specific group of amino acid called branched chain amino acids. ![]()
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