What is Congenital Disorder of Glycosylation Type Ic?
Congenital disorders of glycosylation (CDG) are a group of conditions that affect glycosylation, a process that modifies proteins in the body. The CDG-I disease types are caused by defects in various steps of this process. As a result of this, a variety of symptoms may be seen in the CDG-I forms (a-z). CDG-Ic is caused by harmful genetic changes (mutations) in the ALG6 gene, which leads to build-up of toxic proteins in the cell. CDG-Ic is the second most common CDG disorder, accounting for approximately 9% of reported CDG cases.
CDG-Ic affects many systems of the body, particularly the nervous system, resulting in poor muscle tone, developmental delay, behavioral problems, and intellectual disability in almost all cases. Brain abnormalities, impaired ability to coordinate movement, and seizures are also common. Many affected individuals have poor growth, autistic or behavioral problems, distinctive physical features, and skeletal abnormalities. Skeletal abnormalities include shortening of fingers and toes, limited joint extension, short arms, and scoliosis. Other symptoms, like bleeding problems, 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 has been reported in at least 89 individuals (most of Caucasian descent), but the global incidence is unknown. Milder presentations of CDG-Ic may be under-diagnosed and not yet recognized.
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. Laboratory tests are often used for monitoring of other functions in the body.
What is the prognosis for an individual with Congenital Disorder of Glycosylation Type Ic?
Some individuals 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.