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.