Diseases & Conditions


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Congenital Disorders of Glycosylation Type Ia


Synonyms of Congenital Disorders of Glycosylation Type Ia
  • CDG1A
  • CDGS Type Ia
  • Disorder of N-Glycan Synthesis Ia
  • Hypoglycosylation Syndrome Type Ia

Disorder Subdivisions



    General Discussion
    Since the original publication of the NORD report on this disorder, the standard name was changed from carbohydrate-deficient glycoprotein syndrome to congenital disorders of glycosylation syndrome (CDGS). CDGS refers to a group of rare inherited metabolic disorders that share similar but not identical genetic changes (mutations) and biochemical characteristics. These disorders involve the metabolic activity of glycoproteins, complex chemical compounds created by attaching a simple or complex sugar molecule (glycolization) to a specific protein. Glycoproteins play key roles in the development and maintenance of the cell membrane, endocrine glandular function, and protein transport, and are active in specific parts of the brain (Golgi apparatus). Attaching the sugar to the protein is a process involving many enzymes, and a shortage or lack of any one of these enzymes causes the build-up of intermediate chemical compounds. The accumulation of these compounds is the triggering device of the disorder. Congenital disorders of glycosylation may affect many different parts of the body but are most serious when they involve the central and peripheral nervous systems.

    Recently, medical researchers have agreed to classify the disorder into two major groups. This is based on the chemical pathway in which the defect occurs (mutation leading to an enzyme failure). For the sake of clarity, the disorders that are a result of a faulty enzyme before the sugar molecule is attached to the protein (upstream) are known as Type I disorders. The disorders that arise due to failure in the metabolic process after the sugar molecule has been attached to proteins are known as Type II disorders.

    There appear to be 12 distinct disorders (subtypes) within Type I and there are 5 distinct disorders within Type II. Of all the CDGS disorders, regardless of type, CDGS Type Ia comprises about 70% of all cases.

    Glycoproteins have several important functions in the body. They play a role in the complex chemical processes that enable the body to function normally. Examples include signaling how cells in the body are to interact with one another, participating in the transfer of nutrients from one part of the body to another (transport), playing a role in the proper coagulation of blood, functioning as hormones that regulate certain organs or activities in the body (i.e., endocrine activities that help to regulate the rate of growth, sexual development, and/or metabolism), etc.

    CDGS Type Ia affects several different organ systems. Especially affected are the central nervous system (i.e., the brain and spinal cord), the peripheral nervous system (i.e., motor and sensory nerves outside the central nervous system), and the liver, in which many of the glycoproteins in the blood are made. Although the severity and range of symptoms may vary from case to case, most affected individuals exhibit severe delays in the acquisition of skills that require the coordination of mental and muscular activity (psychomotor retardation); moderate to severe mental retardation; impaired coordination and balance (cerebellar ataxia) due to underdevelopment (hypoplasia) of certain portions of the brain (cerebellum); impaired nerve transmission to the legs, resulting in progressive, severe muscle thinning and weakness (peripheral neuropathy); skeletal malformations; and/or visual and/or hearing impairment. CDGS Type Ia is inherited as an autosomal recessive genetic trait.

    Organizations related to Congenital Disorders of Glycosylation Type Ia
    • American Speech-Language-Hearing Association
      10801 Rockville Pike
      Rockville MD 20852
      Phone #: 800-321-2742
      800 #: 800-321-2742
      e-mail: actioncenter@asha.org
      Home page: http://www.asha.org
    • CDG Family Network
      PO Box 860847
      Plano TX 75086
      Phone #: N/A
      800 #: 800-250-5273
      e-mail: cdgaware@aol.com
      Home page: http://www.cdgs.com
    • CLIMB (Children Living with Inherited Metabolic Diseases)
      Climb Building
      Crewe Intl CW2 6BG
      Phone #: +44- 87-0 7700 325
      800 #: --
      e-mail: info@climb.org.uk
      Home page: http://www.CLIMB.org.uk
    • NIH/National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse
      1 AMS Circle
      Bethesda MD 20892-3675
      Phone #: 301-495-4484
      800 #: 877-226-4267
      e-mail: NIAMSinfo@mail.nih.gov
      Home page: http://www.niams.nih.gov/Health_Info
    • National Association for Parents of Children with Visual Impairments (NAPVI)
      P.O. Box 317
      Watertown MA 02472
      Phone #: 617-972-7441
      800 #: 800-562-6265
      e-mail: napvi@perkins.org
      Home page: http://www.napvi.org
    • National Association for Visually Handicapped
      22 West 21st Street
      New York NY 10010
      Phone #: 212-889-3141
      800 #: --
      e-mail: staff@navh.org
      Home page: http://www.navh.org
    • National Institute of Neurological Disorders and Stroke (NINDS)
      31 Center Drive
      Bethesda MD 20892-2540
      Phone #: 301-496-5751
      800 #: 800-352-9424
      e-mail: braininfo@ninds.nih.gov
      Home page: http://www.ninds.nih.gov/
    • Swedish CDG Society
      S?nnarsl?vsv?gen 130-7
      Tollarp Intl SE-290 10
      Phone #: +46- 44- 310873
      800 #: --
      e-mail: Rolf.Odselius@cdgs.info
      Home page: http://www.cdgs.info/indexeng.shtml
    • United Leukodystrophy Foundation
      2304 Highland Drive
      Sycamore IL 60178
      Phone #: 815-895-3211
      800 #: 800-728-5483
      e-mail: office@ulf.org
      Home page: http://www.ulf.org/
    • Vaincre Les Maladies Lysosomales
      2 ter avenue de Fance
      Massy None 91300
      Phone #: 01 -69 -75 40 30
      800 #: --
      e-mail: accueil@vml-asso.org
      Home page: http://www.vml-asso.org



    For a Complete Report

    This is an abstract of a report from the National Organization for Rare Disorders, Inc. ? (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html