In countries where National newborn screening (NBS) for MSUD is available, early diagnosis is now possible and treatment can be given immediately upon diagnosis to reduce the risk of serious complications. With early diagnosis and the correct treatment, the outcome can be greatly improved. Depending on severity, some individuals may require life-long support in certain aspects of life. Some individuals with early diagnosed, well-managed MSUD, who haven’t suffered prolonged periods of elevated leucine, can enjoy the same expectations in life (in terms of education, employment and family life) as everybody else. Meeting these milestones will depend on the severity of their MSUD, degree of clinical presentation, when treatment is commenced and their dietary compliance.

MSUD is commonly classed according to its severity; “Classical”, “Intermittent” or “Thiamin responsive” MSUD. The severity of the disorder will dictate the degree of protein restriction and BCAA supplementation. The metabolic team will be able to expand and explain this in more detail.

If symptoms occur before diagnosis, they can include sudden, progressive illness with poor feeding, lethargy, unresponsiveness and seizures leading to coma. First signs of MSUD might include the characteristic smell of maple syrup in the baby’s nappy.

Prolonged delay of diagnosis and/or treatment can result in developmental delay, neurological problems, severe brain damage, physical impairment and in some instances death.