There are several forms of MSUD, which vary in severity:
Classic MSUD: The most severe form, presenting in the first few days of life. Intermediate MSUD: Milder symptoms that may appear later in infancy or childhood. Intermittent MSUD: Symptoms occur only during periods of illness or stress. Thiamine-Responsive MSUD: A rare form that may improve with high doses of thiamine (vitamin B1).
