Approximately 1 - 2% of patients with MM have two monoclonal proteins with distinct heavy and/or light chain types (e.g. IgGk and IgAk), termed
biclonal gammopathy (Section 17.1
. The light chain types differ between the dominant and minor clones in around three quarters of cases . In most patients, an increase in κ or λ sFLC concentration is observed and is mediated by the dominant clone, leading to an abnormal sFLC ratio. However, in a small proportion of biclonal patients, an abnormal sFLC ratio results from the minor clone producing monoclonal sFLCs, and in a few patients κ/λ sFLC ratios are normal (Figure 7.8.) .