The clustering of chromosomal gains (1q21, 5p15/5q35, 9q34, 11q23, 15q22, 17p13, and 19q13) in an oncogenetic tree model of AL ± MM I and MGUS/MM I. The complete dataset with all 7 branches tested is complete in 243 of 246 AL and in 173 of 180 MGUS/MM I patients. At least one of the 7 investigated aberrations was detected in 58% (n = 140) of the evaluable AL patients and in 60% (n = 104) of the MGUS/MM I patients. The length of each horizontal edge e is proportional to −log(p_e). Bootstrap confidence values (in percentage) for the inner nodes are given, based on 500 bootstrap samples. In addition to the clusters shown in the graph for gains in the AL group, gains of 15q22 and 17p13 were identified as a separate cluster in 42% of the bootstrap samples and gains of 9q34 and 17p13 built a cluster in 41% of samples; in another 23%, 15q22 was added to the cluster of 9q34 and 17p13. For MGUS/MM I cases, gains of 19q13 and 17p13 were grouped together in 65% of the 500 bootstrap samples, whereas 5p15 and 17p13 were separately clustered in 21% of samples. In 22% of samples, we observed a terminal cluster of 5p15 together with 15q22.