Charlotte G. Nyvold

Lymphoid malignancies are characterized by clonal cell expansion, often identifiable by unique immunoglobulin rearrangements. Heavy (IGH) and light‐chain gene usage offers diagnostic insights and enables sensitive residual disease detection via next‐generation sequencing. With its adaptable throughput and variable read lengths, Oxford Nanopore thirdgeneration sequencing now holds promise for clonotyping. This study analyzed CD138+ plasma‐cell DNA from eight multiple myeloma patients, comparing clonotyping performance between Nanopore sequencing, Illumina MiSeq, and Ion Torrent S5. We demonstrated clonotype consistency across platforms through Smith‐Waterman local alignment of nanopore reads. The mean clonal percentage of IGH V and J gene usage in the CD138+ cells was 69% for Nanopore, 67% for S5, and 76% for MiSeq. When aligned with known clonotypes, clonal cells averaged a 91% similarity, exceeding 85%. In summary, Nanopore sequencing, with its capacity for generating millions of high‐quality reads, proves effective for detecting clonal IGH rearrangements. This versatile platform offers the potential for measuring residual disease down to a sensitivity level of 10 ‐6 at a lower cost, marking a significant advancement in clonotyping techniques.