What is Congenital Disorder of Glycosylation Type Ic?
Congenital disorders of glycosylation are a group of conditions that affect glycosylation, a process that is necessary to diversify the function of proteins in the body. The CDG-I disease types are a result of defects in various steps of the glycoslyation process. As a result of this impairment, a variety of symptoms may be seen in the CDG-I forms (a-z); CDG-Ic results from a defect in the glucosyltransferase I enzyme.
CDG-Ic affects many systems of the body, notably the nervous system, resulting in poor muscle tone, developmental delay, and intellectual disability in almost all cases. Brain malformations, impaired ability to coordinate movement, and seizures are also common. Many affected individuals have poor growth, autistic or behavioral problems, certain physical features, and skeletal abnormalities. Physical features include deep-set eyes, forehead narrowing, broad nasal bridge, shortened region above lip, and wide-spaced eyes. Skeletal abnormalities include shortening of fingers and toes, limited joint extension, short arms, and scoliosis. Other symptoms like deep vein thrombosis, enlarged liver and spleen, enlarged heart, protein loss in the intestines, or pubertal abnormalities, may occur but are less typical.
How common is Congenital Disorder of Glycosylation Type Ic?
CDG-Ic is a rare disorder, but may be the second most common form of congenital disorder of glycosylation. Though it has been reported in at least 89 individuals (most of Caucasian descent), the global incidence is unknown. Other presentations of CDG-Ic may not be recognized as of yet.
How is Congenital Disorder of Glycosylation Type Ic treated?
There is no cure for CDG-Ic; management of the condition involves treating symptoms of the disease. Early intervention and education planning may help improve cognition. Medications may help to control seizures. Parents of a young child with CDG-Ic should ensure the child gets the best possible nutrition to help with growth; some children will require a feeding tube. Early use of occupational, physical, and speech therapy may be helpful in improving the child's long-term abilities in these areas. However, wheelchairs and other movement aids are often useful and become necessary. If non-surgical interventions do not work, surgical measures with proper management to minimize risk for blood clots may correct crossed eyes and scoliosis. Laboratory tests are often used for monitoring of other functions in the body.
What is the prognosis for a person with Congenital Disorder of Glycosylation Type Ic?
Up to 25% of people with CDG-Ic die in infancy or early childhood, often due to infection, seizures, or protein loss in the intestines. Most individuals that live into adulthood will require a wheelchair. Adults are unlikely to be able to live independently, but most will be able to speak, albeit with some impairment, and be able to accomplish certain tasks independently.