Quality Control and Quality Assurance in Biochemical Genetics Laboratory Testing

Biochemical genetics laboratories aim to diagnose or exclude Inherited Metabolic Disorders (IMD), or to monitor therapy in already diagnosed patients. They face specific challenges: IMD are individually rare, but more than a thousand different disorders are known. Hence, laboratories must acquire and maintain sufficient experience to perform diagnostic tests and interpret results for a substantial number of different IMD. To achieve these goals, laboratory testing includes quantitative assays to measure specific analytes and qualitative tests to investigate groups of metabolites semi-quantitatively. To assess performance and compliance to Standardised Operating Procedures (SOPs), Internal Quality Control (IQC), and External Quality Assurance (EQA) programmes that review both quantitative and qualitative assays are essential. IQC is generally implemented by the laboratories themselves. Most EQA for quantitative and qualitative assays is provided by ERNDIM. In addition, as interpretation of results is an important part of the activity of biochemical genetics laboratories, ERNDIM develops interpretative EQA schemes that allow review of the competence of individuals, which is a real benefit in the context of laboratory accreditation. This chapter discusses how IQC and EQA can be used to assess and optimise precision, accuracy, and correct interpretation of test results.