Serum free light chains are used to assist in the diagnosis of multiple myeloma. The test measures kappa (K) and lambda (L) chains, and the calculation of the ratio of kappa to lambda (K/L). Previous studies have shown that the K/L ratio does not change over time (1 year). The hypothesis of this study is that healthy twins will have a K/L ratio that are close to each other in value, suggesting that this ratio is genetically linked.
