Introduction to laboratory diagnosis and biomarkers in inborn error of metabolism

Inborn errors of metabolism (IEM) are genetic disorders of intermediary metabolism that result in metabolic defects due to deficiency of enzymes, membrane transporters, or other functional proteins. Many of these disorders are detected through newborn screening or clinical suspicion. Laboratory tests and use of biomarkers are essential in the diagnosis and follow-up of patients with IEM. Specialized tests are not available in most hospitals, and need special attention in specimen collection, processing, and transport. Routine tests, although not necessarily diagnostic, are important in initial patient management and in providing guidance for further testing and management. Furthermore, there may be conditions that present with biochemical findings that mimic or confound a diagnosis. Unlike routine laboratory tests that are generally automated, most biochemical genetics tests are developed in-house. Method development and quality control can be challenging due to lack of standardized reagents and limited availability of external assessment programs. Treatment and prognosis of these disorders varies significantly, from dietary management to enzyme replacement therapies.