Congenital Disorders of Glycosylation (CDG)

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What are congenital disorders of glycosylation (CDG)?

Congenital disorders of glycosylation (CDG) is a group of rare disorders that affect how sugars attach to proteins and fats in the body. The process of making and attaching these sugars is called glycosylation. People with CDG cannot make or attach these sugars or sugar chains properly.

This happens because of changes in 1 of the involved in glycosylation. Doctors have identified more than 100 forms of CDG, with different genetic causes. These include PMM2-CDG, ALG1-CDG, PIGT-CDG, PIGA-CDG and MPI-CDG. In a disorder called NGLY1-CDDG, the body has trouble taking sugar chains off some proteins.

The disorders may affect many parts of your child’s body, such as their brain, nerves, muscles, liver and . Symptoms can range from mild to life-threatening. Although glycosylation involves sugar, CDG conditions are not related to diabetes.

Biochemical Genetics at Seattle Children's

Our Biochemical Genetics team provides a long-term "medical home" for babies, children and young adults with known or suspected inherited metabolic disorders.

What are the symptoms of CDG?

Symptoms depend on the type of CDG your child has and which body systems it affects. The severity of symptoms varies even among children with the same type of CDG. 

  • Symptoms in babies and children
    • Floppy muscle tone
    • Poor growth
    • Liver disease
    • Abnormal bleeding or blood clotting
    • Crossed or misaligned eyes
    • Changes in the brain that can be seen on brain imaging
    • Heart problems
  • Symptoms in teens and young adults
    • Problems with balance and coordination (ataxia)
    • Slurred speech
    • disability
    • Worsening curvature of the spine (scoliosis)
    • Joint
    • Vision problems
    • Differences in

How are CDG conditions diagnosed?

CDG can be hard to diagnose. These disorders are rare and cause a wide range of symptoms. If your child has multiple unexplained health concerns, CDG may be the cause.

During a full diagnostic evaluation we will:

  • Ask about your child’s symptoms, development and medical history.
  • Ask if anyone else in your family has had the same kind of symptoms.
  • Check your child for signs of CDG. These include changes in body fat, enlarged liver or spleen and differences in facial features, speech or movement.
  • Test your child’s blood to look for of CDG.
  • Check your child’s blood or spit (saliva) for some of the gene changes that cause specific CDG conditions. Our will explain the test options and what to expect.

Your child’s healthcare team can explain the type of CDG your child has and what it may mean for your child and family.

How are CDG conditions treated?

We tailor care to your child’s needs. At this time, there is no cure for most types of CDG. But we can manage the health problems CDG may cause. Our goal is to help your child have the best possible function and quality of life — now and as they grow.

The team in our Biochemical Genetics CDG Specialty Clinic and experts across Seattle Children’s will treat your child. When possible, your child sees their entire team on a single day, to make the process easier for your family.

  • Nutrition and growth support
    • Our and doctors partner to help your child achieve their full growth and For some types of CDG, nutrition therapy is the cornerstone of medical treatment.
    • Babies who have trouble gaining weight may need high-calorie formula, by mouth or through a feeding tube.
    • Many children with CDG have problems with feeding, vomiting or . Some babies may need a placed through the wall of their belly directly into their stomach.
    • Our feeding therapists will help your child develop strong swallowing and feeding skills.
    • We help manage diets by mouth, through feeding tubes or by IV into a vein if needed during acute illness.
    • We may recommend specific types of sugar supplements for some forms of CDG.
  • Developmental delays
    • Most types of CDG affect the nervous system, causing .
    • Starting early with , and can help your child have their highest possible quality of life. Most children need therapy until adulthood and beyond.
  • Bleeding or clotting
    • Some children with CDG have problems with bleeding too easily or blood clotting.
    • If needed, a blood specialist (hematologist) will treat your child with medicines or .
  • Vision
    • Many children with CDG have misaligned eyes (strabismus) or crossed eyes. Your child may need eye patches, glasses or surgery, depending on any problems they have.
    • As an adult, a pigment at the back of your child’s eye (retinitis pigmentosa) may affect their vision.
    • An eye specialist (ophthalmologist) will check your child’s vision regularly.
  • Heart health
    • In some people with CDG, fluid may collect around the heart (pericardial effusion) or the heart muscle may be too thick or stiff (cardiomyopathy).
    • Your child may need an to check their heart health. A heart specialist will follow up if your child needs regular checkups.
    • If there are problems, treatment options include medicine, fluid drainage or surgery.
    • Our Heart Center has more than 40 pediatric with experience diagnosing and treating kids in a child-focused, healing environment.
  • Seizures
    •  affect children with some forms of CDG. Doctors in our Epilepsy Program have access to many medicines, including some new options being studied in .
    • If your child’s seizures do not respond to medicine, your doctor may recommend surgery to remove the abnormal brain tissue.
  • Liver function
    • Many forms of CDG affect the liver, especially in the first few years of life. Some types of CDG cause lifelong liver problems.
    • As needed, we will do regular blood tests and refer your child to Seattle Children’s liver specialists for treatment.
  • Support and social work
    • Our helps your child and family with coping, social relationships, behavior and emotions.
    • We will connect you with helpful resources at Seattle Children’s and in the community.

Why choose Seattle Children’s for your child’s CDG care?

  • The patient advocacy group CDG Care recognizes Seattle Children’s as a Congenital Disorders of Glycosylation Specialty Clinic because of the high quality of care and support we provide.
  • Because these disorders are so rare, many doctors have little experience with CDG. Our team has the expertise and experience to diagnose your child’s form of CDG and give them the best care.
  • We are the only children’s hospital in the Pacific Northwest named a Rare Disease Center of Excellence by the National Organization for Rare Disorders (NORD). At NORD Centers of Excellence like ours, experienced teams of world-class doctors diagnose and treat a wide range of rare diseases.
  • Our Biochemical Genetics team provides a “medical home” for your child. Many children born with metabolic disorders need lifelong care to have the best possible quality of life. We help your family manage your child’s disease over the long term. Our team of doctors, , nurses, and provide support and resources.
  • We offer of new treatments and invite our patients to take part in , studies and that collect medical information about children with CDG. We work with other researchers in the Frontiers in CDG Consortium to improve care for people with these rare disorders.
  • We serve children, teens and young adults across the WWAMI region and beyond. WWAMI includes Washington, Wyoming, Alaska, Montana and Idaho.

Contact Us

If you would like an appointment, ask your primary care provider or specialist to refer you to Seattle Children’s Biochemical Genetics. If you have a referral, contact us at 206-987-3012, option 1 to make an appointment.

Providers, see how to refer a patient to Biochemical Genetics.

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