Fluorescence in situ hybridization probe validation for clinical use

In this chapter, we provide a systematic overview of the published guidelines and validation procedures for fluorescence in situ hybridization (FISH) probes for clinical diagnostic use. FISH probes—which are classified as molecular probes or analyte-specific reagents (ASRs)—have been extensively used in vitro for both clinical diagnosis and research. Most commercially available FISH probes in the United States are strictly regulated by the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), the Centers for Medicare & Medicaid Services (CMS) the Clinical Laboratory Improvement Amendments (CLIA), and the College of American Pathologists (CAP). Although homebrewed FISH probes—defined as probes made in-house or acquired from a source that does not supply them to other laboratories—are not regulated by these agencies, they too must undergo the same individual validation process prior to clinical use as their commercial counterparts. Validation of a FISH probe involves initial validation and ongoing verification of the test system. Initial validation includes assessment of a probe’s technical specifications, establishment of its standard operational procedure (SOP), determination of its clinical sensitivity and specificity, development of its cutoff, baseline, and normal reference ranges, gathering of analytics, confirmation of its applicability to a specific research or clinical setting, testing of samples with or without the abnormalities that the probe is meant to detect, stafftraining, and report building. Ongoing verification of the test system involves testing additional normal and abnormal samples using the same method employed during the initial validation of the probe.