Maple Syrup Urinary Disorder (MSUD) is a genetic disorder caused by a mutation resulting from a deficiency in one of the six proteins that form collectively branched-chain alpha-ketoacid dehydrogenase. (BCKD) (Genetic Sciences Learning Center). MSUD is characterized by increased plasma levels of branched-chain amino acids and excretion of branched-chain keto acids producing a maple syrup aroma (Pangkanon, Charoensiriwatana and Sangtawesin 41-43). MSUD is an autosomal recessive disorder, meaning that an individual must inherit one copy of the MSUD gene from both parents to be affected. There are currently five clinical classifications for MSUD phenotypes based on dietary protein tolerance, clinical presentation and trials, enzyme levels, and response to thiamine. The five phenotypes are: classic, intermediate, intermittent, thiamine sensitive, and E3 deficient. The classic form of MSUD is the most common form and represents 75% of MSUD patients. The classic form is also the most severe of the five phenotypic forms. Depending on the severity, several symptoms are characteristic of MSUD. Symptoms may be mild, such as weakness, feeding problems, and lethargy, or symptoms may be severe, such as seizures, mental retardation, delayed motor development, and brain edema. The severity of an individual's symptoms corresponds to the form of MSUD they have. People with untreated classic MSUD die within the first few months due to persistent metabolic abnormalities and neurological degeneration. There is currently no cure for MSUD; however, it can be treated with lifelong dietary management and aggressive management during delicate metabolic cycles. MSUD is a rare disease afflicted...... middle of paper ...... found before these tests. This resulted in the complete deletion of exon six in the mRNA. Works Cited Georgiou, Theodoros, Jacinta Chuang, Max Wynn, Goula Stylianidou, Mark Korson, DavidChuang and Anthi Drousiotou. "Maple syrup urinary disease in Cypriot families: identification of three novel mutations and biochemical characterization of the p.Thr211Met mutation in the E1α subunit." PubMed Central. (2009): no. page. Internet. December 4, 2011. “New mutation”. Home reference on genetics. United States National Library of Medicine, 28 11 2011. Web.4 December 2011. .Pangkanon, uthipong, Wiyada Charoensiriwatana and Varaporn Sangtawesin. “Maple Syrup Urinary Sickness in Thai Infants.” Journal of Medical Associations of Thailand. 91. (2008): 41-43. Print.