Indeed, a comparison of the relative frequencies of class-switched isotypes (i.e., excluding IgD/M BCRs) showed a significant enrichment of IgA1/2 isotypes and a reduced relative frequency of IgG1/2 in malignant CLL clones compared to healthy repertoires (p-value < 0.005) (Figure 4B). Here, IGHA1 is linked to B-cell chronic lymphocytic leukemia.