Maple Syrup Urine Disease

NewsRx Bundle A quick and inexpensive way to view the most recent articles for a one-time project. Custom Reports on Maple Syrup Urine Disease Tired of prepackaged reports that just don't meet your needs? Target your needs!

What is maple syrup urine disease?

Maple syrup urine disease is an inherited disorder in which the body is unable to process certain protein building blocks (amino acids) properly. Beginning in early infancy, this condition is characterized by poor feeding, vomiting, lack of energy (lethargy), seizures, and developmental delay. The urine of affected infants has a distinctive sweet odor, much like burned caramel, that gives the condition its name. Maple syrup urine disease can be life-threatening if untreated.

Maple syrup urine disease can be classified by its pattern of signs and symptoms or by its genetic cause. The most common and most severe form of the disease is the classic type, which appears soon after birth. Variant forms of the disorder appear later in infancy or childhood and are typically milder, but still involve mental and physical retardation if not treated.

How common is maple syrup urine disease?

Maple syrup urine disease affects an estimated 1 in 185,000 infants worldwide. The disorder occurs much more frequently in the Old Order Mennonite population, in which the incidence is about 1 in 358 newborns.

What genes are related to maple syrup urine disease?

Mutations in the BCKDHA, BCKDHB, DBT, and DLD genes cause maple syrup urine disease.

These four genes provide instructions for making proteins that work together as a complex. This complex is essential for breaking down the amino acids leucine, isoleucine, and valine, which are present in many kinds of food (particularly protein-rich foods such as milk, meat, and eggs). Mutations in any of these genes reduce or eliminate the function of the complex, preventing the normal breakdown of leucine, isoleucine, and valine. As a result, these amino acids and their byproducts build up in the body. Because high levels of these substances are toxic to the brain and other organs, their accumulation leads to the serious medical problems associated with maple syrup urine disease.

How do people inherit maple syrup urine disease?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder each carry one copy of the altered gene but do not show signs and symptoms of the disorder.

Source: National Institutes of Health

Studies from Stanford University, Department of Pathology update current data on microarray

"For comprehensive carrier screening and molecular diagnostic purposes, we developed a population-specific and inclusive microarray. The arrayed primer extension genotyping microarray carries 59 sequence variant detection sites, of which 53 are detectable bi-directionally. These sites represent the most common variants in Tay-Sachs disease, Bloom syndrome, Canavan disease, Niemann-Pick A, familial dysautonomia, torsion dystonia, mucolipidosis type IV, Fanconi anemia, Gaucher disease, factor XI deficiency, glycogen storage disease type 1a, maple syrup urine disease, nonsyndromic sensorineural hearing loss, familial Mediterranean fever, and glycogen storage disease type III. Several mutations in the selected disorders that are not prevalent per se in the Ashkenazi Jewish populations, as well pseudodeficiency alleles, are also included in the array. The initial technical evaluation of this microarray demonstrates that it is comprehensive, robust, sensitive, specific, and easily modifiable," wrote I. Schrijver and colleagues, Stanford University, Department of Pathology.

The researchers concluded: "This cost-effective array is based on a diversely applied platform technology and is suitable for both carrier screening and disease detection in Ashkenazi and Sephardic Jewish populations."

Schrijver and colleagues published their study in the Journal of Molecular Diagnostics (Comprehensive arrayed primer extension array for the detection of 59 sequence variants in 15 conditions prevalent among the (Ashkenazi) Jewish population. Journal of Molecular Diagnostics, 2007;9(2):228-36).

For more information, contact I. Schrijver, L235, Dept. of Pathology, Stanford University Medical Center, 300 Pasteur Dr., Stanford, CA 94305 USA.

Publisher contact information for the Journal of Molecular Diagnostics is: American Society Investigative Pathology, Inc., 9650 Rockville Pike, Bethesda, MD 20814-3993, USA.

Keywords: United States, Stanford, Diagnostics, Microarray.

This article was prepared by Gastroenterology Week editors from staff and other reports. Copyright 2007, Gastroenterology Week via NewsRx.com.