Annotating the next generation sequencing report

With the advent of precision oncology, the number of genetic alterations to be tested in tumor biopsies has significantly increased. Consequently, many clinical laboratories are incorporating multiplexed techniques, such as next generation sequencing (NGS). Even if limited panels are used, NGS analysis of a tumor biopsy usually detects a large number of variations that need to be annotated. Annotation means identifying the functional and clinical relevance of the variants in order to identify the actionable alterations that can predict sensitivity/resistance to therapies or alter prognosis. This review gives an overview of the annotation process, with particular emphasis in its clinical relevance and potential pitfalls.