LA JOLLA, Calif., May 10, 2013 Children born with rare, inherited conditions known as Congenital Disorders of Glycosylation, or CDG, have mutations in one of the many enzymes the body uses to decorate its proteins and cells with sugars. Properly diagnosing a child with CDG and pinpointing the exact sugar gene that's mutated can be a huge relief for parentsthey better understand what they're dealing with and doctors can sometimes use that information to develop a therapeutic approach. Whole-exome sequencing, an abbreviated form of whole-genome sequencing, is increasingly used as a diagnostic for CDG.
But researchers at Sanford-Burnham Medical Research Institute (Sanford-Burnham) recently discovered three children with CDG who are mosaicsonly some cells in some tissues have the mutation. For that reason, standard exome sequencing initially missed their mutations, highlighting the technique's diagnostic limitations in some rare cases. These findings were published April 4 in the American Journal of Human Genetics.
"This study was one surprise after another," said Hudson Freeze, Ph.D., director of Sanford-Burnham's Genetic Disease Program and senior author of the study. "What we learned is that you have to be carefulyou can't simply trust that you'll get all the answers from gene sequencing alone."
Searching for a rare disease mutation
Complicated arrangements of sugar molecules decorate almost every protein and cell in the body. These sugars are crucial for cellular growth, communication, and many other processes. As a result of a mutation in an enzyme that assembles these sugars, children with CDG experience a wide variety of symptoms, including intellectual disability, digestive problems, seizures, and low blood sugar.
To diagnose CDG, researchers will test the sugar arrangements on a common protein called transferrin. Increasingly, they'll also look for known CDG-related mutations by whole-exome seque
|Contact: Patrick Bartosch|
Sanford-Burnham Medical Research Institute