Congenital disorder of glycosylation type I/IIX (CDG-x) is a part of a group of rare inherited conditions that are present at birth (congenital) and involve errors in the glycosylation pathway. The term CDG-x is an umbrella term that may refer to any Congenital Disorder of Glycosylation (CDG) that has not yet been specifically diagnosed, but presents symptoms similar to those of other CDGs. The CDG are typically categorized as either type 1 or type 2 based on where in the glycosylation pathway the defect occurs. Glycosylation involves the joining of sugars and proteins (to form glycoproteins) by enzymes (proteins that function to convert specific substances in the body) in the cells of our bodies. These sugars (glycans) must be properly attached to specific proteins in the cells in order for the cells to function correctly. Due to the many functions of these glycoproteins throughout the body, if an error occurs in one of the many steps of the process, a wide variety of health problems will occur beginning in infancy. Because CDG-x may refer to any number of unidentified CDGs, the symptoms vary greatly. Common symptoms associated with a CDG include psychomotor delays, mental retardation, and distinct physical characteristics that also vary, but may include a small head circumference and eye abnormalities. Symptoms associated with CDG-x may also include seizures and changes in skin pigment, although these were not always reported.
Because CDG-x is not a single condition, treatment options are determined on a case by case basis until the final diagnosis is made. It is estimated that 20% of individuals diagnosed with a CDG have not yet been assigned a type or specific diagnosis. Talk to your doctor or a geneticist if someone in your family has been diagnosed with a CDG.