BMC Cancer 2009, 9:438 http://www.biomedcentral.com/1471-2407/9/438 SMRT is by far the most polymorphic of the 4 coregula- tors. A recent study suggests that mutation rate, compared to selection pressure, has a larger impact on polymor- phism frequency in a region [20]. Further, areas of con- densed chromatin have been suggested to have the highest level of background mutation [21]. Together this suggests that SMRT is under less selective pressure than NCoR and/or is in a region of the genome with a higher Table 3: Associations according to age stratification mutation rate (possibly in an area of condensed chroma- tin). Genotyping for Association with Breast Cancer Risk We genotyped a case-control study of female index patients of BRCA1/BRCA2 mutation negative breast can- cer families for two SNPs in SRC-3 which were previously shown to have a protective effect for breast cancer [15] (rs2230782 and rs2076546). Additionally, we genotyped SNP Genotypes Cases Controls Odds ratios (OR) with 95% confidence intervals (95% CI) and P-values. Page 6 of 9 (page number not for citation purposes) SRC-1 rs1804645 P1272S SRC-3 rs6094752 C218R SRC-3 rs2230782 Q586H SRC-3 rs2076546 T960T SMRT rs2229840 A1706T SRC-1 rs1804645 P1272S SRC-3 rs6094752 C218R SRC-3 rs2230782 Q586H SRC-3 rs2076546 T960T SMRT rs2229840 A1706T CC (%) CT (%) TT (%) CC (%) CT (%) TT (%) GG (%) GC (%) CC (%) AA (%) AG (%) GG (%) GG (%) AG (%) AA (%) CC (%) CT (%) TT (%) CC (%) CT (%) TT (%) GG (%) GC (%) CC (%) AA (%) AG (%) GG (%) GG (%) AG (%) AA (%) Cases and Controls ≥50 306 (93.9) 747 (94.9) 20 (6.1) 40 (5.1) 0 (0.0) 0 (0.0) [CT + TT]<-> [CC] 299 (92.8) 691 (89.0) 20 (6.2) 80 (10.4) 3 (1.0) 5 (0.6) [CT + TT]<-> [CC] 253 (78.1) 623 (79.4) 68 (21.0) 150 (19.1) 3 (0.9) 12 (1.5) [CC]<-> [GG + GC] 270 (83.6) 653 (82.5) 52 (16.1) 126 (15.9) 1 (0.3) 12 (1.6) [AG + GG]<-> [AA] 222 (69.4) 517 (67.0) 89 (27.8) 220 (28.5) 9 (2.8) 35 (4.5) [AG + GG]<-> [AA] Cases and Controls < 50 682 (94.4) 685 (94.9) 38 (5.3) 37 (5.1) 2 (0.3) 0 (0.0) [CT + TT]<-> [CC] 633 (88.6) 639 (89.4) 77 (10.8) 72 (10.1) 4 (0.6) 4 (0.6) [CT + TT]<-> [CC] 592 (82.2) 584 (81.3) 122 (16.9) 122 (17.0) 6 (0.9) 12 (1.7) [CC]<-> [GG + GC] 592 (82.1) 587 (81.7) 123 (17.1) 123 (17.1) 6 (0.8) 8 (1.2) [AG + GG]<-> [AA] 470 (66.9) 487 (68.4) 202 (28.8) 203 (28.5) 30 (4.3) 22 (3.1) [AG + GG]<-> [AA] OR 1 1.22 - 1.22 1 0.58 1.39 0.62 1 1.12 0.62 0.60 1 0.99 0.20 0.93 1 0.94 0.59 0.89 1 1.03 - 1.08 1 1.08 1.01 1.08 1 0.98 0.49 0.49 1 0.99 0.74 0.98 1 1.03 1.41 1.07 95% CI 0.70-2.12 - 0.70-2.12 0.35-0.96 0.33-5.84 0.39-1.01 0.81-1.54 0.17-2.20 0.16-2.14 0.70-1.42 0.02-1.56 0.66-1.31 0.70-1.26 0.28-1.27 0.68-1.18 0.65-1.64 - 0.69-1.72 0.77-1.52 0.25-4.05 0.77-1.50 0.75-1.30 0.18-1.32 0.18-1.32 0.75-1.30 0.26-2.16 0.75-1.28 0.82-1.30 0.80-2.48 0.85-1.33 P 0.479 - 0.479 0.033 0.654 0.053 0.502 0.451 0.429 0.991 0.088 0.676 0.689 0.175 0.439 0.896 - 0.725 0.658 0.989 0.665 0.923 0.152 0.153 0.952 0.584 0.862 0.796 0.228 0.561