Table 2.
Group usage and SHM rates in IGHV genes.
| IGHV group | Expected frequency | Observed frequency | Median SHM % (95% CI) |
|---|---|---|---|
| IGHV1 | 10 (18.2%) | 55 (15.2%) | 10.0 (8.6–10.5) |
| IGHV2 | 3 (5.4%) | 31 (8.6%) | 6.5 (6.0–8.0) |
| IGHV3 | 26 (47.3%) | 191 (52.7%) | 8.8 (8.7–9.7) |
| IGHV4 | 12 (21.8%) | 67 (18.5%) | 9.2 (9.2–11.4) |
| IGHV5 | 2 (3.6%) | 18 (5.0%) | 7.2 (6.1–9.0) |
| IGHV6 | 1 (1.8%) | 0 | – |
| IGHV7 | 1 (1.8%) | 0 | – |
| Total | 55 | 362 | 8.8 (8.8–9.6) |
| Comparison of SHM % | Adjusted p value | ||
|---|---|---|---|
| IGHV1 vs. IGHV2 | 0.006 | ||
| IGHV2 vs. IGHV4 | 0.001 | ||
| IGHV2 vs. IGHV3 | 0.012 | ||
| IGHV1 vs. IGHV5 | 0.301 | ||
| IGHV4 vs. IGHV5 | 0.118 | ||
| IGHV3 vs. IGHV5 | 0.790 | ||
| IGHV1 vs. IGHV4 | 1 | ||
| IGHV2 vs. IGHV5 | 1 | ||
| IGHV3 vs. IGHV4 | 1 | ||
| IGHV1 vs. IGHV3 | 1 | ||
The first two columns show the expected IGHV gene usage if all genes were randomly selected compared with the observed frequency within our cohort, respectively. Observed and expected IGHV distributions were not different when the χ2 test was applied, demonstrating that there is no evidence of selection of specific gene groups in myeloma. Median somatic hypermutation rates per IGHV group are shown on the right side of the table. Below, Kruskal−Wallis-based paired comparisons are listed to determine potential differences in the hypermutation rate; a significantly lower mutation rate was found for patients using IGHV2 compared to those using IGHV1 (p = 0.006), IGHV3 (p = 0.012) and IGHV4 (p = 0.001).
95% CI 95% confidence intervals.