Members Login
Search
Wednesday, Dec 03, 2008 | 11:43 AM
Madisons Foundation - Moms And Dads In Search Of Needed Support
Maple Syrup Urine Disease
Branched-Chain Ketoaciduria
Sunday, 20 July 2003
Last Updated Tuesday, 12 July 2005
What
Maple syrup urine disease (MSUD) is an inherited, genetic disorder in which the body does not break down certain molecules called amino acids. amino acids are important molecules that make up the various proteins for our bodies. amino acids are important for many functions such as growth and development. The amino acids that cannot be broken down in MSUD are leucine, isoleucine, and valine (called branched chain amino acids or BCAAs). Normally, some of the protein that we eat is used for growth. The remainder is then used for energy. In MSUD, the body cannot use the BCAAs for energy. Because they cannot be used, the BCAAs build up in the body and become toxic. This toxicity causes mental retardation, physical disabilities, and can lead to death. This condition is so-named because the urine of an affected person smells like maple syrup.Who
MSUD occurs in all ethnic groups and equally affects males and females. The disease occurs in about 1 in 225,000 births and even more often in the Mennonite population in Pennsylvania.Signs and Symptoms
Infants with MSUD initially have a poor appetite, irritability, and urine that smells like maple syrup or burnt sugar. Within days after birth, they cannot suck well, are limp or lethargic, have a high-pitched cry, and episodes where they are tense or stiff (rigidity). Without treatment, symptoms can progress to seizures, coma, and even death. Stress on the body such as illness and infection can also cause these symptoms to occur. In milder forms of the disease, severe symptoms usually occur only during times of illness.Possible Causes
There are several different genes that have been found to cause MSUD. These genes are located on chromosomes 1, 6, and 19. MSUD is inherited in an autosomal recessive manner. When the child’s genes have a change (or mutation), the body does not make certain proteins (called enzymes) that break down the BCAAs. Since the body cannot break down the BCAAs into energy, they build up and interfere with brain function. The severity of symptoms that the child has depends on how much enzyme the child’s body is missing. There are several different types of MSUD: classic, intermediate, intermittent, and thiamine-responsive. In classic MSUD, there is little or no enzyme activity and symptoms usually occur within the first days of life. In intermediate MSUD, there is more enzyme activity than in the classic type so that more protein can be tolerated. In intermittent MSUD, there is even more enzyme activity and symptoms often do not occur until one to two years of age. This is because toddlers normally start eating more protein or get sick more often. In thiamine-responsive MSUD, treating the child with a vitamin called thiamine can help the body have normal enzyme activity.Diagnosis
In some states, a blood test is performed on all newborns to screen for MSUD and other conditions (newborn screening). In other states, infants are diagnosed only after they start having symptoms. In this case, a blood or urine test can be done to check the level of BCAAs. The amount of enzyme activity in the body can also be measured to confirm the diagnosis. This condition can also be diagnosed on an unborn baby during pregnancy (prenatally), by testing the amniotic fluid (fluid that surrounds the baby).Treatment
The child should be followed by a metabolic geneticist who specializes in these types of conditions. They should also have a metabolic dietician who is familiar with the special nutritional needs of the child. Initially, an infant with MSUD is treated to quickly reduce the levels of BCAAs in the body. This involves giving intravenous (IV) fluids of glucose and other types of amino acids except for BCAAs. The IV fluids provide the body with different substances that can be used for energy since it cannot use the BCAAs. It is important that this treatment begin soon after birth to decrease the risk of life-threatening complications and reduced intellectual development. Long-term treatment involves maintaining a carefully controlled diet that limits protein to prevent BCAAs from building up. Initially, infants are given limited amounts of BCAAs for normal growth and development. There is a special formula designed for children with MSUD that provides good nutrition but does not contain BCAAs. This restriction of protein in the foods they eat should continue throughout their life. The child’s growth and development should be closely monitored. If too much protein is eaten, or if the child has an infection, fever or other illness, BCAAs can accumulate very quickly. In these cases, prompt treatment is needed to decrease the level of BCAAs so that they do not cause damage to the brain. The methods available include hemodialysis or peritoneal dialysis (treatments that remove harmful substances from the blood). Some individuals have had a liver transplantation performed. This will allow the child to eat a fairly normal diet because the new liver contains the enzyme that was missing. However, having a liver transplant is a major surgery that has complications. Also, the child would need to be on lifelong medications every day. The decision to have a liver transplant versus simply staying on a protein restricted diet should be weighed carefully by the parents and physicians.Prognosis
Children with MSUD can lead relatively healthy, normal lives with early diagnosis and treatment, strict dietary management, and regular medical care.Connect with other parents
In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.Weblinks
Maple Syrup Support Group
Provide information and support services to those affected by MSUD.
Mead Johnson
Contains information on MSUD, with a good dietary management section.
National Coalition for PKU and Allied Dosorder
A great website with information about the disease as well as links to support group and other resources.
Mead Johnson
Contains information on MSUD, with a good dietary management section.
Access Medicine
A good resource for your healthcare provider.