• Inherited Metabolic Diseases—Overview


    This topic refers to rare genetic metabolic defects. When a defect occurs, it is because enzymes (proteins important for cells in your body to function correctly):
    • Are missing from the body or
    • Are not functioning normally
    In some cases, extra chemicals or waste build up in the body. This causes symptoms. In other cases, there is a lack of vital substance or protein.
    There are thousands of inherited metabolic diseases, such as:


    These diseases are caused by a genetic defect passed on from parent(s) to child.
    Genetic Material
    Chromosome DNA
    Copyright © Nucleus Medical Media, Inc.

    Risk Factors

    Risk factors include:
    • Family history
    • Certain ethnic backgrounds (Ashkenazi Jewish, Finnish, Dutch)


    Symptoms can be severe and appear shortly after birth. Symptoms can also be mild and detected later in life. Tell your doctor if your child has any of these:
    • Distorted facial features
    • Enlarged tongue
    • Cloudy eyes
    • Purple-blue skin rash
    • Swollen abdomen
    • Skeletal deformities
    • Short stature
    • Lack of muscle control
    • Seizures
    • Decreased motor skills
    • Developmental delays
    • Intellectual disability
    These symptoms may be caused by other conditions. If your child has any of these, talk to the doctor.


    The doctor will:
    • Ask about your child’s symptoms and medical history
    • Do a physical exam
    • Work with specialists to diagnose the condition
    • Order tests, such as:
      • Enzyme testing (skin, blood, urine)
      • Screening tests for vision and hearing
      • Electroretinogram—measures response of cells in the retina of the eye
      • Neuropsychological testing—measures mental function
      • MRI scan —a test that uses magnetic waves to make pictures of structures inside the brain, may be done along with another test called magnetic resonance spectroscopy (MRS)
      • Spinal tap —fluid is taken from the spine and examined
      • Tissue biopsy —a sample of tissues is taken and examined
      • Electromyogram (EMG)—measures electrical impulses in the muscles with a thin needle electrode
      • Other special tests of the heart, liver, and kidneys
    Before your baby is born, prenatal tests can check for metabolic diseases.


    Talk with the doctor about the best treatment plan for your child. Treatment will depend on the type of condition your child has. Options may include:


    Your child may need to have changes made to his diet, like avoiding certain foods. Also, avoiding long periods of not eating may help. Taking vitamins may also be beneficial.

    Ongoing Symptom Management

    To manage symptoms and other conditions, your child may need:
    • Dialysis
    • Physical therapy
    • Surgery
    • Medicines

    Substrate Synthesis Inhibition Therapy (SSI)

    This is a special medicine to help the body make less cell waste.

    Enzyme Replacement Therapy (ERT)

    A missing enzyme is given through a needle placed in the vein (IV).

    Bone Marrow Transplant

    Healthy bone marrow is transplanted into your child. This may help his body function and slow how fast the disease progresses.

    Ongoing Monitoring

    For some conditions, regular annual screening tests will be needed, such as:


    There is no way to prevent these kinds of disorders. Prenatal testing and newborn screening may help with early detection.


    Children Living with Inherited Metabolic Disorders http://www.climb.org.uk/

    Society for Inherited Metabolic Disorders http://www.simd.org/


    The Canadian Society for Mucopolysaccharide & Related Diseases http://www.mpssociety.ca/

    Health Canada http://www.hc-sc.gc.ca/index%5Fe.html/


    Badash M. Glycogen storage diseases. EBSCO Patient Education Reference Center website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=16&topicID=1034 . Updated May 28, 2010. Accessed August 6, 2010.

    Lysosomal Disease Network website. Available at: http://www.lysosomaldiseasenetwork.org/ . Accessed August 6, 2010.

    Mayo Clinic. Metabolic Disorders. Mayo Clinic website. Available at: http://www.mayoclinic.org/metabolic-disorders/ . Accessed August 9, 2010.

    National Information Center for Metabolic Diseases (CLIMB) website. Available at: http://www.climb.org.uk/ . Accessed August 9, 2010.

    Revision Information

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