#MAPLE SYRUP URINE DISEASE CODE#
MSUD can result from mutations in any of the genes that code for the enzyme subunits. The E3 subunit is also a component of pyruvate dehydrogenase complex and oxoglutarate dehydrogenase complex. The enzyme complex consists of four subunits designated E1α, E1β, E2, and E3. MSUD is a metabolic disorder caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKDC), leading to a buildup of the branched-chain amino acids ( leucine, isoleucine, and valine) and their toxic by-products (ketoacids) in the blood and urine. The parents of a child with an autosomal recessive disorder are carriers of one copy of the defective gene, but are usually not affected by the disorder. This condition has an autosomal recessive inheritance pattern, which means the defective gene is located on an autosome, and two copies of the gene – one from each parent – must be inherited to be affected by the disorder.
Because high levels of these substances are toxic to the brain and other organs, this accumulation leads to the serious medical problems associated with maple syrup urine disease. As a result, these amino acids and their by-products build up in the body. Mutation in any of these genes reduces or eliminates the function of the enzyme complex, preventing the normal breakdown of isoleucine, leucine, and valine. These are present in some quantity in almost all kinds of food, but in particular, protein-rich foods such as dairy products, meat, soy, gluten, eggs, nuts, whole grains, seeds, avocados, algae, edible seaweed, beans, and pulses. The complex is essential for breaking down the amino acids leucine, isoleucine, and valine. These four genes produce proteins that work together as the branched-chain alpha-keto acid dehydrogenase complex. DLD ( Online Mendelian Inheritance in Man (OMIM) 238331).DBT ( Online Mendelian Inheritance in Man (OMIM) 248610).BCKDHB ( Online Mendelian Inheritance in Man (OMIM) 248611).BCKDHA ( Online Mendelian Inheritance in Man (OMIM) 608348).Mutations in the following genes cause maple syrup urine disease: Maple syrup urine disease has an autosomal recessive pattern of inheritance. In more rare cases, concomitant osteoporosis may also appear in these patients. Additionally, maple syrup urine disease patients often experience an abnormal course of disease in simple infections that become increasingly severe and can have permanent damage. Without prompt treatment, they will likely die from cerebral edema. Untreated in older individuals, and during times of metabolic crisis, symptoms of the condition include uncharacteristically inappropriate, extreme or erratic behaviour and moods, hallucinations, anorexia, weight loss, anemia, diarrhea, vomiting, dehydration, lethargy, oscillating hypertonia and hypotonia, ataxia, seizures, hypoglycaemia, ketoacidosis, opisthotonus, pancreatitis, rapid neurological decline, and coma. The symptoms of MSUD may also present later depending on the severity of the disease. Death often occurs within the first five months in severe cases of the disease, when left untreated. Infants with this disease seem healthy at birth but quickly deteriorate, often with severe brain damage, which may be permanent. In populations to whom maple syrup is unfamiliar, the aroma can be likened to fenugreek, and fenugreek ingestion may impart the aroma to urine.
The smell is also present and sometimes stronger in the ear wax of an affected individual at these times.
The disease is named for the presence of sweet-smelling urine, an odor similar to that of maple syrup, when the person goes into metabolic crisis. The condition gets its name from the distinctive sweet odor of affected infants’ urine, particularly prior to diagnosis, and during times of acute illness. Maple syrup urine disease (MSUD), also called branched-chain ketoaciduria, is an autosomal recessive metabolic disorder affecting branched-chain amino acids.
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