Fluorescence in situ hybridization (FISH) in diagnostic and investigative neuropathology

Over the last decade, fluorescence in situ hybridization (FISH) has emerged as a powerful clinical and research tool for the assessment of target DNA dosages within interphase nuclei. Detectable alterations include aneusomies , deletions, gene amplifications, and translocations, with primary advantag es to the pathologist including its basis in morphology, its applicability to archival, formalin-fixed paraffin-embedded (FFPE) material, and its simi larities to Immunohistochemistry. Recent technical advances such as Improve d hybridization protocols, markedly expanded probe availability resulting f rom the human genome sequencing initiative, and the advent of high-throughp ut assays such as gene chip and tissue microarrays have greatly enhanced th e applicability of FISH. In our lab, we currently utilize only a limited ba ttery of DNA probes for routine diagnostic purposes, with determination of chromosome 1p and 19q dosage in oligodendroglial neoplasms representing the most common application. However, research applications are numerous and w ill likely translate into a growing list of clinically useful markers in th e near future. In this review, we highlight the advantages and disadvantage s of FISH and familiarize the reader with current applications In diagnosti c and investigative neuropathology.