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Maple Syrup Urine Disease
Maple syrup urine disease (MSUD) is a genetic condition that affects children worldwide but is most common in Old Order Mennonites. Triggered by a mutation in three specific genes, MSUD causes a buildup of three specific amino acids (leucine, isoleucine and valine) which reach toxic levels in the brain and organs—triggering a variety of complications. Maple syrup urine disease gets its name from the resulting unique sweet odor of an infant’s urine. It effects 1 out of every 380 babies of Mennonite origin and 1 out of every 185,000 births worldwide.
What Are the Symptoms of MSUD?
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In most cases, symptoms of MSUD will be apparent soon after birth but some children may not begin to show signs until weeks or months after being born. Thankfully, testing for Maple Syrup Urine Disease is now standard in the United States for all newborns and is completed during the routine newborn screening blood work 24 hours after birth. There are several types of MSUD ranging from severe and nearly sudden onset (between 24 hours and two weeks of life) to delayed onset (as late as 7 years of age), but time of onset does not hinder side effects. The most common symptoms of MSUD include:
- Feeding difficulties
- Developmental and neurological delays
- Urine with a sweet smell
If left untreated, infants with classic MSUD will die in the first months of life – this statistic reinforces the need for prompt diagnosis. Delaying diagnosis for just 14 days can cause irreversible mental damage. Depending on the type of the condition, some patients can live in to their teen and childbearing years with varying degrees of disability.
How Is MSUD Managed?
Patients with MSUD can be managed to a degree with a special diet free from the amino acids their body cannot break down. This means following a low protein diet (meat, eggs and milk are high in leucine, valine and isoleucine) and hospitalization if needed for fluids and supportive therapies to treat other symptoms. In some cases dialysis may be needed and liver transplantation has shown benefit for some patients. MSUD can be made worse by physical stress (such as an infection or illness) so patients may need additional intensive care during these times.
A special diet will be necessary throughout the patient’s life and it must be followed strictly. Babies will need a special manmade formula—breastfeeding is not possible—and a team approach should be used to care for these children. That means close supervision by physicians, dieticians and of course great commitment from the child’s caregivers.
Can Maple Syrup Urine Disease Be Prevented?
Because MSUD is genetic, it’s important for men and women who are considering having children and may be carriers for the condition to consider genetic screening. For MSUD to develop in a baby, both the mom and dad must carry the gene for MSUD. Pathway Genomics is one provider of genetic carrier testing that can provide valuable information revealing if one or both parents carry the gene. Couples can coordinate testing options with their family physician and then consider their options. It may be a good idea to consult a trusted healthcare provider and a genetic counselor to learn more about the disease and its management before making any family planning decisions.