• Comprise a big class of genetic diseases dealing with congenital disorders of metabolism. A huge part of the diseases are due to single gene defects that code for enzymes that help conversion of various substances (substrates) into others (products).
  • In most of the disorders, problems appear because of substance build-up which are toxic or interfere with normal function, or to the effects of decreased ability to synthesize essential compounds.
  • Other names: congenital metabolic diseases, inherited metabolic diseases.

Symptoms may include:

  • Growth failure, failure to thrive, weight loss.
  • Ambiguous genitalia, delayed puberty, precocious puberty.
  • Developmental delay, seizures, dementia, encephalopathy, stroke.
  • Deafness, blindness, pain agnosia.
  • Skin rash, abnormal pigmentation, lack of pigmentation, excessive hair growth, lumps and bumps.
  • Dental abnormalities.
  • Immunodeficiency, low platelet count, low red blood cell count, enlarged spleen, enlarged lymph nodes.
  • Many forms of cancer.
  • Recurrent vomiting, diarrhea, abdominal pain.
  • Excessive urination, kidney failure, dehydration, edema.
  • Low blood pressure, heart failure, enlarged heart, hypertension, myocardial infarction.
  • Liver enlargement, jaundice, liver failure.
  • Unusual facial features, congenital malformations.
  • Excessive breathing (hyperventilation), respiratory failure.
  • Abnormal behavior, depression, psychosis.
  • Joint pain, muscle weakness, cramps.
  • Hypothyroidism, adrenal insufficiency, hypogonadism, diabetes mellitus.


  • Physician may do/request:
    • History & Physical Exam
    • Screening tests such as:
      • Mass Spectrometry
      • Ferric chloride test
      • Ninhydrin paper chromatography
      • Guthrie bacterial inhibition assay Quantitative measurement of amino acids in plasma and urine
    • Specific diagnostic tests (or focused screening for a small set of disorders):
      • Tissue biopsy or necropsy
      • Skin biopsy and fibroblast cultivation
    • Specific DNA testing



  • Dietary restriction
    • Reduction of dietary protein for phenylketonuria and other amino acid disorders.
  • Dietary supplementation or replacement
    • Oral ingestion of cornstarch several times a day for people with glycogen storage diseases to prevent hypoglycemia.
  • Vitamins
    • Thiamine supplementation for several types of disorders that cause lactic acidosis.
  • Intermediary metabolites, compounds, or drugs that facilitate or retard specific metabolic pathways.
  • Dialysis
  • Enzyme replacement
  • Gene therapy
  • Bone marrow or organ transplantation
  • Treatment of symptoms and complications
  • Prenatal diagnosis

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