Synthetic nutrient formulas are available for affected MSUD infants for proper growth and development lacking BCAAs. The treatment involves lifelong maintenance of a restricted diet to control the levels of BCAAs in the body. There is no cure for MSUD but dietary changes can be accommodated to reduce the effects and complications of the disease. These testing can be made necessary for at-risk relatives to detect carriers and prenatal diagnosis for at-risk pregnancies. Molecular genetic testing for mutations in the BCKDHA, BCKDHB, DBT and DLD genes is rarely available to confirm the diagnosis. Prenatal detection is done either through chorionic villus biopsy or by amniocentesis. Similar to all inborn errors, infants with mild forms of the disorder can be missed by newborn screening as their amino acid levels may remain within normal range initially. Tandem mass spectrometry has aided in the diagnosis of MSUD by measuring BCAAs levels. Newborn screening programs also help in detecting MSUD. Plasma BCAAs and urine organic acids are carried out initially as confirmatory tests. The maple syrup odor in an infant’s urine is a very peculiar feature that, together with appropriate symptoms, can be diagnostic enough to start therapy. The prevalence of MSUD is 1 in 100,000 in India. The disorder’s estimated incidence is about 1 in 380 newborns, occurring much more frequently in the Old Order Mennonite population. Maple syrup urine disease affects an estimated 1 in 185,000 infants worldwide. If a person is a carrier for the disease (one defective allele), he/she doesn’t show symptoms. When defective alleles of genes are inherited by the infant from both the parents, it leads to occurrence of symptoms. MSUD follows autosomal recessive inheritance. MSUD is caused by changes or mutations in one of four different genes: BCKDHA, BCKDHB, DBT and DLD which lead to absent or decreased activity of human branched-chain alpha-ketoacid dehydrogenase complex (BCKAD) enzymes. It is beneficial by boosting residual enzyme activity but would still need dietary restrictions. Affected infants respond to large doses of thiamine, which plays a role in the BCAA enzyme complex. It is similar to Intermediate MSUD but responds to treatment with thiamine (vitamin B1). These infants experience symptoms when in stress during some infection. It is usually characterized by normal growth and intellectual development. Symptoms are similar to those of the classical form and are susceptible to the same degree of neurologic complications as those with classic MSUD. The onset and symptoms of intermediate MSUD can be neonatal or identified later in life around 5 months to 7 years. Intermediate MSUD is characterized by greater levels of residual enzyme activity than observed in classic MSUD. Further classic MSUD can lead to respiratory failure leading to fatality.
The infant’s condition further deteriorates with the progression of disease and then starts to show neurological defects with increasing hypertonia and spasticity leading to seizures and coma. Most infants with classic MSUD show symptoms within 2-3 days. The most common and most severe form is classic MSUD in which there is little to no enzyme activity. alternating episodes of hypertonia (muscle rigidity) and hypotonia (muscle limpness).
a distinctive maple sugar odor in earwax, sweat, and urine.If untreated, this disease can lead to seizures, coma, and death. The following symptoms include poor feeding, vomiting, lack of energy (lethargy), abnormal movements, and delayed development. This odor usually can be detected within a few days of childs’ birth. It is first characterized by the sweet smelling odor of infants’ urine. Absence of this enzyme leads to increased levels of BCAAs in the body causing physical and neurological disorders. BCAAs are commonly found in foods rich in protein, such as meat, eggs, and milk.
This enzyme complex is lacking in the MSUD affected infants. The condition has this name from the peculiar sweet odor of affected infants’ urine.īCKDC (branched-chain alpha-keto acid dehydrogenase complex) is an enzyme which processes three important amino acids: leucine, isoleucine, and valine, also called BCAAs (branched-chain amino acids). Maple Syrup Urine Disease (MSUD) is a rare inherited metabolic disorder in which the body cannot process certain amino acids properly leading to their accumulation.
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