Maple Syrup Urine Disease (MSUD)
Test
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Bacterial inhibition assay for leucine
Genetics
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Autosomal recessive
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1:250,000 to 1:400,000 in US
-
1:760 Mennonites
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Higher in Americans of African or Asian ethnicity
Pathology
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Disorder of branched-chain ketoacid decarboxylation resulting in high body
fluid (serum, urine, and spinal fluid) levels of leucine, isoleucine, valine
and their corresponding ketoacids.
Diagnosis
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Characteristic smelling urine
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When plasma leucine levels are extremely elevated, early neonatal symptoms
include poor feeding, seizures, coma and ketoacidosis
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The intermediate form is associated with mental retardation and ataxia,
but not ketoacidosis
-
In addition to mental retardation, spastic quadriparesis, dystonic posturing,
dysarthria and poor physical growth are common
-
Death within the first 2 weeks is not uncommon. Some patients die
suddenly at older ages despite therapy
Treatment
-
Dietary restriction of branched-chain amino acids, continued throughout
life. Best outcomes (least mental retardation) are seen when treatment
is begun within 24 hours of symptoms
Acknowledgment
This page is based on a 1998 presentation by Owen Rennert, Georgetown University
Medical Center, Department of Pediatrics, Division of Genetics.
Also see other Inborn Errors of Metabolism.
Please direct all comments to: 
Last modification: January 10, 2000