MSUD causes an accumulation of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine, and related ketoacids. Accumulation of these compounds (especially leucine) disturbs brain cell volume regulation and results in brain edema and secondary impairment of neuron growth, myelin synthesis, and cerebral neurotransmitter production leading to physical and intellectual disability and, if untreated, death.
In addition to the classic form, there are variant forms of the disease – intermediate, intermittent, and thiamine responsive – which may have milder and later onset of symptoms, presenting with anorexia, poor growth, irritability, seizures, or developmental delay in late infancy or childhood. Symptoms and metabolic crisis episodes may be precipitated by illnesses or excess protein intake.
Sotero de Menezes MA, Connolly M, Bolanos A, Madsen J, Black PM, Riviello JJ Jr.
Temporal lobectomy in early childhood: the need for long-term follow-up.
J Child Neurol. 2001;16(8):585-90. PubMed abstract
Puckett RL, Lorey F, Rinaldo P, Lipson MH, Matern D, Sowa ME, Levine S, Chang R, Wang RY, Abdenur JE.
Maple syrup urine disease: further evidence that newborn screening may fail to identify variant forms.
Mol Genet Metab. 2010;100(2):136-42. PubMed abstract
|Author:||Nicola Longo, MD, PhD - 2/2012|
|Compiled and edited by:||Lynne M Kerr, MD, PhD - 2/2012|
|Content Last Updated:||4/2012|
The authors listed above are responsible for the overall Maple Syrup Urine Disease (MSUD) Module. Authors contributing to individual pages in the module are listed on those pages.
Carleton SM, Peck DS, Grasela J, Dietiker KL, Phillips CL.
DNA carrier testing and newborn screening for maple syrup urine disease in old order mennonite communities.
Genet Test Mol Biomarkers. 2010;14(2):205-8. PubMed abstract