This protocol seeks to enroll smoldering multiple myeloma (SMM) and monoclonal gammopathy of undetermined significant (MGUS) patients with λ light chain (LC) involvement, a group of patients for whom standard of care is observation not treatment. Patients with SMM and MGUS have a precursor plasma cell disorder from which light chain amyloidosis (AL) can evolve. In this trial, enrolled subjects will have blood and if available bone marrow cells evaluated by molecular testing to determine their clonal λ LC variable region (VL) germline gene. Seventy percent of AL cases involve just 7 germline donors, 5 of which are λ germline donors. The hypothesis that will be tested with this protocol is that the presence of AL germline genes associated with AL in patients with a pre-existing diagnosis of λ SMM or λ MGUS indicates the presence of AL or risk of progression to AL.