Characteristics of the participants
| Population controls | Family-based cases | Family-based cases: subset* | |
| n | 3474 | 3918 | 1968 |
| Families | 3492 | 1602 | |
| Relatives per family included | |||
| 1 | 3474 | 3099 | 1263 |
| 2 | 0 | 364 | 309 |
| 3 | 0 | 25 | 25 |
| 4 | 0 | 4 | 3 |
| Study | |||
| ABCS | 1563 | 904 | 82 |
| HEBON | 0 | 2248 | 1671 |
| ORIGO | 987 | 0 | 0 |
| RBCS | 924 | 766 | 215 |
| Array | |||
| GSA | 1781 | 1781 | |
| iCOGS | 2388 | 1680 | 163 |
| OncoArray | 1086 | 457 | 24 |
| Age | |||
| Mean | 45.6 | 45.1 | 46.8 |
| Range | 18–93 | 21–91 | 21–91 |
| First breast cancer | |||
| Invasive | NA | 3575 | 1630 |
| In situ | NA | 312 | 308 |
| Unknown | NA | 31 | 30 |
| ER status | |||
| Positive | NA | 1755 | 927 |
| Negative | NA | 488 | 213 |
| Unknown | NA | 1675 | 828 |
| Second breast tumour (n) | NA | 719 | 327 |
| Age | |||
| Mean | NA | 52.6 | 52.9 |
| Range | NA | 26–80 | 26–79 |
| Unknown | NA | 130 | 29 |
| Invasiveness | |||
| Invasive | NA | 460 | 220 |
| In situ | NA | 116 | 77 |
| Unknown | NA | 144 | 30 |
| ER status | |||
| Positive | NA | 290 | 153 |
| Negative | NA | 49 | 21 |
| Unknown | NA | 380 | 153 |
| Gene panel results | |||
| All | 2584 | 2586 | 1586 |
| No PV | 2537 | 2369 | 1463 |
| CHEK2 PV | 31 | 167 | 98 |
| ATM PV | 9 | 39 | 18 |
| CHEK2+ATM PV | 0 | 2 | 1 |
| PALB2 PV† | 7 | 10 | 6 |
| Standardised PRS313 (SD) | |||
| Overall BC | 0 (1.03) | 0.71 (0.96) | 0.64 (0.88) |
| ER+ BC | 0 (1.03) | 0.72 (0.97) | 0.65 (0.88) |
| ER− BC | 0 (1.01) | 0.45 (0.94) | 0.29 (0.85) |
| BOADICEAFH | |||
| Mean (SD) | 0 (0.99) | 0.55 (0.39) | 0.69 (0.35) |
| Affected FDR | |||
| 0 | NA | 1125 | |
| 1 | NA | 1454 | |
| 2 | NA | 555 | |
| >2 | NA | 176 | |
| Affected SDR | |||
| 0 | NA | 1360 | |
| 1 | NA | 1086 | |
| 2 | NA | 583 | |
| >2 | NA | 281 | |
| Unknown | NA | 615 | |
*Cases included in the association analyses which were not part of the development data set for the PRS313 as described in Mavaddat et al.5
†Excluding variants in the last exon of PALB2 to make it uniform for all 2586 cases.
ABCS, Amsterdam Breast Cancer Study; BC, breast cancer; BOADICEAFH, polygenic load calculated in the Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm; ER, Estrogen Receptor; FDR, first-degree relatives; GSA, Global Screening Array; HEBON, Hereditary Breast and Ovarian cancer study in the Netherlands; n, number of individuals; NA, Not Applicable; ORIGO, Oorsprong van borstkanker integraal onderzocht; PRS, Polygenic Risk Score; PV, pathogenic variant; RBCS, Rotterdam Breast Cancer Study; SDR, second-degree relatives.