The term Maple Syrup Urine Disease includes a range of classic and variant types of the disorder. The symptoms of classic MSUD are usually evident within the first week of life and include a poor appetite, irritability, and the characteristic odor of the urine. Within days, the infants may lose their sucking reflex and grow listless, have a high-pitched cry, and become limp with episodes of rigidity. Without diagnosis and treatment, symptoms progress rapidly to seizures, coma, and death. Variant forms of MSUD are milder, but the symptoms can be severe during an illness and lead to a metabolic crisis. In variant types, failure to thrive may be the first symptom noticed.