Maple syrup urine disease (MSUD) is a rare disorder that some people are born with, though it can also show up later during childhood.
Children’s Hospital of Philadelphia notes that the condition is extremely uncommon, affecting roughly one in 185,000 births worldwide. When it isn’t recognized and treated quickly, MSUD can become life-threatening.
“If not diagnosed and treated soon after birth, maple syrup urine disease (MSUD) can be life threatening – as early as the first two weeks of life,” the hospital says.
MSUD develops when the body cannot properly break down three specific amino acids found in protein: leucine, isoleucine and valine. When these amino acids accumulate to dangerous levels, they can become toxic and cause severe harm.
Cleveland Clinic states: “These amino acids build up, become toxic and cause severe health problems. Without medical management, MSUD can lead to a wide range of intellectual and physical disabilities.
“It can be fatal without proper management.”
In many cases, signs of the disorder begin to appear in early childhood, often before a child turns seven. Signs of MSUD in children include:
Without treatment, MSUD can progress into what’s known as a “metabolic crisis,” where the body’s ability to process food and maintain normal chemical balance breaks down.
Symptoms linked to a metabolic crisis can include unusual muscle movements, seizures or convulsions, vomiting, and loss of consciousness leading to coma.
Anyone experiencing a metabolic crisis needs urgent medical care, as the condition can be fatal if not treated promptly.
According to Children’s Hospital of Philadelphia, MSUD is typically caused by an inherited genetic mutation affecting one of three genes: BCKDHA, BCKDHB or DBT. A child with MSUD will have received the mutation from their parents.
“These genes provide instruction for the human body to make enzymes (BCKDH complex enzymes) which are essential for breaking down amino acids including leucine, isoleucine, and valine,” it explains further.
Those amino acids are present in many protein-heavy foods, including milk, meat and eggs.
Most cases are first flagged through routine newborn screening programs, which can detect early indicators of MSUD shortly after birth.
After an initial screen, diagnosis is confirmed through additional testing. This may include blood and urine tests, genetic studies, or ESI-Time of Flight mass spectrometry, which measures leucine, isoleucine and valine levels in a baby’s blood.