Biochemical Genetics - Inborn Errors of Metabolism

Genetic disorders play an increasingly greater role in clinical medicine. In the aggregate, 6% to 8% of diseases among hospitalized children have been ascribed to Mendelian traits inherited as single gene defects. Hundreds of inborn errors of metabolism (IEM) have been identified to date, primarily through the detection of endogenous metabolites abnormally accumulated in biological fluids and tissues.

The clinical impact of biochemical genetics is driven by the constant expansion of the number of metabolites and enzyme activities that can be assayed in human body fluids and tissues for diagnostic purposes. Consequently, testing for hereditary metabolic disorders has developed from a highly specialized and fragmented activity, provided mostly by research-oriented scientists, to a critical component at the forefront of the laboratory work-up of patients of all ages.

The Mayo Clinic Biochemical Genetics Laboratory is an interdisciplinary group of laboratorians, geneticists, and physicians with a mission to provide biochemical testing and result interpretation and consultation of the highest quality for the diagnosis, study, and clinical care of patients with a broad spectrum of IEM.

The laboratory offers close to 150 procedures for the screening, biochemical diagnosis, and carrier detection, when applicable, of many IEM, which include disorders of:

• Amino acid metabolism
• Carbohydrate metabolism such as galactosemia
• Congenital disorders of glycosylation
• Cholesterol biosynthesis
• Cofactor and vitamin metabolism
• Lysosomal metabolism and storage
• Mitochondrial energy metabolism (primary lactic acidemias)
• Fatty acid metabolism (mitochondrial ß-oxidation) and carnitine homeostasis
• Organic acid disorders
• Peroxisomal biogenesis and metabolism
• Porphyrin metabolism
• Purine and pyrimidine metabolism
• Urea cycle disorders
• Disorders of creatine metabolism

Procedures for the qualitative detection and quantitative determination of diagnostic markers are based on a variety of methods:

• Thin-layer chromatography (TLC)
• High-performance liquid chromatography (HPLC)
• Ion-exchange chromatography
• Capillary gas chromatography
• Gas chromatography-mass spectrometry (GC-MS)
• Tandem mass spectrometry (MS/MS)
• Liquid chromatography-tandem mass spectrometry (LCMS/MS)
• Colorimetric/fluorometric
• Enzyme-linked immunosorbent assay (ELISA)
• Acrylamide electrophoresis

See a complete list of all tests performed in the Biochemical Genetics Laboratory.