Clinical use of next-generation sequencing of TRG gene rearrangements has arrived.

In this issue of the Journal, Schumacher and colleagues1 describe important principles to consider when applying nextgeneration sequencing (NGS) for the identification of clonal sequences to support the diagnosis of T-cell neoplasms. NGS has been shown to be clinically useful in identifying germline mutations in hereditary conditions and somatic mutations in numerous cancers. In 2009, one of the first reports of the use of NGS methods to describe the repertoire of TRB gene rearrangements was published.2 Since then, it has been used to characterize the T-cell repertoire in patients with various diseases. The next application described was the identification of unique sequences of minimal residual disease in acute lymphoblastic leukemia.3,4 It was a logical step to go from defining a T-cell repertoire to the application of NGS in clonality detection, whether at diagnosis1 or in follow-up.3,4