![]() To date, no person with "thiamine-responsive" MSUD has been treated solely with thiamine. In general, such putative individuals have residual ex vivo BCKAD enzyme activity of up to 40% normal and are not ill in the neonatal period, but present later in life with a clinical course similar to intermediate MSUD. It is not known with certainty if individuals with true thiamine-responsive MSUD exist. Basic management principles for such persons do not differ from those with classic MSUD, and the distinction between classic and intermediate types is not absolute. Severe leucinosis, brain swelling, and death can occur if individuals with intermediate MSUD are subjected to sufficient catabolic stress. They are vulnerable to the same acute and chronic neurologic sequelae as persons with the classic form of the disease. The majority of persons with intermediate MSUD are diagnosed between ages five months and seven years. Individuals with intermediate MSUD can present with feeding problems, poor growth, and developmental delay during infancy, or may present much later in life with nonsyndromic intellectual disability. Individuals with residual BCKAD activity (i.e., 3%-30% ex vivo) may appear well during the neonatal period but, nevertheless, have maple syrup odor in cerumen and a consistently abnormal plasma amino acid profile. During infections or other physiologic stress, they can develop the clinical and biochemical features of classic MSUD, in rare cases culminating in coma and death. When they are well, they generally tolerate a normal leucine intake, and plasma amino acid and urine organic acid profiles are normal or show only mild elevations of BCAAs. Intermittent MSUDĬhildren with the intermittent form of MSUD have normal growth and intellectual development throughout infancy and early childhood. This can cause lifelong learning problems, mental retardation or spasticity. Children who have repeated metabolic crises may develop permanent brain damage. during stressful events such as surgeryĮven with treatment, some children still develop swelling of the brain or have episodes of metabolic crisis.Symptoms of a metabolic crisis often happen: high levels of acidic substances in the blood, called metabolic acidosis.episodes where muscles tone alternates between being rigid and floppy.If not treated, other symptoms can follow: Some of the first symptoms of a metabolic crisis are: urine that smells like maple syrup or burnt sugarīabies with MSUD have episodes of illness called metabolic crisis.Symptoms start as soon as a baby is fed protein, usually shortly after birth. E3-Deficient MSUD with Lactic Acidosis SYMPTOMS Classic MSUD.Intermittent MSUD, that is the second most common form of the disorder.The other forms of the disorder may appear later in infancy or childhood and are typically less severe and less common. The three genes associated with MSUD are BCKDHA (E1a subunit gene, MSUD type 1A), BCKDHB (E1b subunit gene, MSUD type 1B), and DBT. The most common and severe type is the classic MSUD, which appears soon after birth. There are a number of different forms of MSUD. ![]() Here, the incidence is estimated of about 1 in 380 newborns. MSUDaffects people of all ethnic backgrounds, but higher rates of the disorder occur in populations in which there is a lot of intermarriage, such as the Mennonite (Amish) community in Pennsylvania (U.S.A.). Maple syrup urine disease occurs in about 1 per 180,000 live births and affects both males and females. Maple syrup urine disease (MSUD) is caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKAD) composed of BCKDHA, BCKDHB, DBT, and DLD, leading to a build-up to toxic levels in the body of the branched-chain amino acids (leucine, isoleucine, and valine). The compound responsible for the odor is sotolon (sometimes spelled sotolone). Maple syrup odor is evident in cerumen soon after birth and in urine by age five to seven days. This condition is one type of amino acid disorder getting its name from the distinctive sweet odor of affected infants' urine. Maple syrup urine disease also called branched-chain ketoaciduria, is an autosomal recessive disorder.
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