ALK testing by FISH in NSCLC tumor tissues without ALK rearrangement may detect rearrangement-positive patterns (i.e. split patterns or isolated 3’ patterns) in a fraction of cells [31-33], likely because of truncation artefact caused by tissue sectioning, or perhaps a stochastic genomic alteration that does not indicate a specific gene fusion. The gene discussed is ALK; the disease is non-small cell lung carcinoma.