TNFSF14 and monoclonal gammopathy: Notably, an abnormal sFLC ratio must be examined in the context of each patient because a significant subset of individuals may have low-grade, non-specific circulating light-chains, and it is not uncommon (20 to 40% of cases) for patients with ATTR CA to also have an unrelated monoclonal gammopathy of undetermined significance (defined as an overgrowth of clonal plasma cells <10% along with a serum monoclonal protein <3 g/dl but without end-organ damage) without overproduction of light-chains33.