Synonyms: Classic BCKD deficiency | Classic MSUD | Classic branched-chain alpha-ketoacid dehydrogenase deficiency | Classic branched-chain ketoaciduria
Classic maple syrup urine disease (classic MSUD) is the most severe and probably common form of MSUD (see this term) characterized by a maple syrup odor in the cerumen at birth poor feeding lethargy and focal dystonia followed by progressive encephalopathy and central respiratory failure if untreated.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version June 2026
Newly diagnosed with
Classic maple syrup urine disease?
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Advocacy Organizations
Canadian PKU and Allied Disorders (CanPKU)
“To improve the lives of people living with PKU and other inherited metabolic disorders by supporting education, advocacy, access to care, and community connection.”
Louisiana Metabolic Disorders Coalition
We support, educate, and advocate for patients & families affected by metabolic disorders.
Mississippi Metabolics Foundation
Our mission at Mississippi Metabolics Foundation (MMF) is to advocate, educate, and support families in MS affected by genetic metabolic disorders/inborn errors of metabolism (IEM's). MMF promotes initiatives and further advancements in legislation, education, research, clinical trials, studies, therapies, targeted treatments, and eventual cures for IEM’s and all rare diseases.
ReNU2 United
ReNU2 United fosters collaboration, supports families, raises awareness, and advances research into RNU2-2-related neurodevelopmental disease.
Uganda Alliance of Patients Organization
Supporting patients to access quality, safe and patient-centered healthcare services.
flok Health (formerly National PKU News)
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Clinical Trials
For a list of clinical trials in this disease area, please click here.