Metabolic & Genetic Descriptions


The information contained in the PDF below is not meant to be comprehensive and definitive in all circumstances but merely to offer an overview to physicians and healthcare providersof genetic and metabolic disorders. Assistance should be sought by contacting a qualified genetic metabolic specialist.

download pdf

Major Categories of Inherited Metabolic Diseases

Traditionally the inherited metabolic diseases were categorized as disorders of carbohydrate metabolism, amino acid metabolism, organic acid metabolism, or lysosomal storage diseases. In recent decades, hundreds of new inherited disorders of metabolism have been discovered and the categories have proliferated. Following are some of the major classes of congenital metabolic diseases, with prominent examples of each class. Many others do not fall into these categories.

  • Disorders of carbohydrate metabolism (glycogen storage disease)
  • Disorders of amino acid metabolism (phenylketonuria, maple syrup urine disease, glutaric acidemia type 1)
  • Urea Cycle Disorder or Urea Cycle Defects (Carbamoyl phosphate synthetase I deficiency)
  • Disorders of organic acid metabolism (organic acidurias) (alcaptonuria)
  • Disorders of fatty acid oxidation and mitochondrial metabolism (Medium-chain acyl-coenzyme A dehydrogenase deficiency (often shortened to MCADD.))
  • Disorders of porphyrin metabolism (acute intermittent porphyria)
  • Disorders of purine or pyrimidine metabolism (Lesch-Nyhan syndrome)
  • Disorders of steroid metabolism (lipoid congenital adrenal hyperplasia, congenital adrenal hyperplasia)
  • Disorders of mitochondrial function (Kearns-Sayre syndrome)
  • Disorders of peroxisomal function (Zellweger syndrome)
  • Lysosomal storage disorders (Gaucher's disease, Niemann Pick disease)


Manifestations and Presentations

Because of the enormous number of these diseases and wide range of systems affected, nearly every "presenting complaint" to a doctor may have a congenital metabolic disease as a possible cause, especially in childhood. The following are examples of potential manifestations affecting each of the major organ systems: many manifestations may develop

  • 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, thrombocytopenia, anemia, enlarged spleen, enlarged lymph nodes
  • Many forms of cancer
  • Recurrent vomiting, diarrhea, abdominal pain
  • Excessive urination, renal failure, dehydration, edema
  • Hypotension, heart failure, enlarged heart, hypertension, myocardial infarction
  • Hepatomegaly, 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