Ketoaciduria, or maple syrup urine disease, also referred to as MSUD, is an inherited metabolic disorder in which the individual affected lacks certain necessary enzymes, causing a buildup of amino acids and keto acids in the body. These acids are unable to be broken down without the missing enzymes, and can cause a range of symptoms, and even life threatening conditions. The most severe and common form of the disease is that that affects infants. In infants, symptoms present shortly after birth, generally within three to four days. Other forms of the disease, which manifest later in childhood, are often less severe and less likely to be life threatening, though they still require treatment. The disease acquired its name from one of its telltale signs in infants: maple syrup scented urine.
In infants with MSUD maple syrup scented urine, vomiting, difficulty with feeding, and lethargy are the main symptoms. Progressive neurologic signs of altering hypotonia and hypertonia are observed in affected infants, signs of a severe encephalopathy. MSUD can cause a “metabolic crisis” through the buildup of toxic substances in the blood, in this case those substances are the short branched-chain alpha keto acids leucine, isoleucine and valine. Symptoms of a metabolic crisis include: poor appetite, nausea, vomiting, diarrhea, extreme sleepiness, irritable mood and behavior changes. Metabolic crisis means that the chemical reactions within the body necessary to maintain the living state of cells are not taking place as necessary. Without treatment breathing problems, seizures, coma, and sometimes even death can occur as a result of metabolic crisis. Infants may often seem fine at birth, but condition quickly deteriorates, often resulting in permanent brain damage once the infants receives treatment and recovers.
When presenting later on in childhood, or even in adulthood, symptoms more commonly include developmental delays, physically and mentally, and interferences in brain development or function. During times of metabolic crisis, symptoms are the same as those of metabolic crisis in infants, as well as hypoglycaemia, ketoacidosis, opisthotonus, and pancreatitis. Without prompt treatment, patients often die from cerebral edema, or the accumulation of excess fluid in either the intracellular or extracellular spaces of the brain. If severe symptoms of disease do not appear early in life, patients instead often have complications in the course of other illnesses or infections which lead to the diagnosis of MSUD, as well as causing an increase of severity of the illness or infection which can lead to permanent damage.
In some places, babies are screened for MSUD after birth, in others they are only diagnosed after symptoms have been recognized. Screening involves testing blood taken from a heel prick in newborns for leucine and isoleucine levels, and a screen positive result for MSUD does not...