Newborn Metabolic Screening Program
Maple Syrup Urine Disease (MSUD)
Amino Acid Disorder:
What is it?
Maple Syrup Urine Disease (MSUD) is a disorder abnormally affecting
the metabolism of amino acids. This disease is treated and managed
very similar to the care of patients with PKU.
disorder affects the way the body metabolizes certain components
of protein. These components are the three branch-chain amino-acids
leucine, isoleucine, and valine. These amino acids accumulate
in the blood causing a toxic effect that interferes with brain
The gene defect for MSUD is an autosomal recessive genetic trait
and is unknowingly passed down from generation to generation.
This faulty gene only emerges when two carriers have children
together and pass it to their offspring. For each pregnancy
of two such carriers, there is a 25% chance that the child will
be born with the disease and a 50% chance the child will be
a carrier for the gene defect.
affects approximately 1 in every 150,000 live births. MSUD was
first described as a disease in 1954. It is believed to be in
all ethnic groups worldwide.
This disease presents very dramatic signs in the newborn period
such as poor feeding, lethargy, convulsions, and even death,
occurring within the first few days of life.
Dietary restrictions must be maintained through the lifetime
of an affected individual.
Treatment requires dietary restriction of branched-chain amino
acids, a special medical formula (drink similar to milk) and
intensive dietary monitoring.