5 Tumor location Colon 77 65.3 6 5.1 71 60.2 Rectum 40 33.9 5 4.2 35 29.7 Both 1 0.8 0 0 1 0.8 Ethnic status Caucasian 98 83.1 10 8.5 88 7.5 African American 14 11.9 1 0.8 13 11.0 Asian 3 2.5 0 0 3 2.5 Hispanic 3 2.5 0 0 3 2.5 Stage at diagnosis Stage 1 11 9.3 1 0.8 10 8.5 Stage 2 30 25.4 5 4.2 25 21.2 Stage 3 44 37.3 1 0.8 43 36.4 Stage 4 33 28.0 4 3.4 29 24.6 Family history No 76 64.4 7 5.9
69 58.5 Yes 34 28.8 3 2.5 31 26.3 Unknown 8 6.8 1 0.8 7 5.9 Association of TGFBR1 SNPs with TGFBR1 allele-specific expression Three SNPs in linkage disequilibrium with each other were strongly associated with TGFBR1 ASE: rs7034462 (p = 7.2 × 10-4), TGFBR1*6A (p = 1.6 × 10-4) and rs11568785 (p = 1.4 × 10-4) (Table 2). TGFBR1*6A is located within the coding sequence of exon 1 and the other two SNPs are located within introns. rs7034462 is located 9.2 kb upstream of exonn 1 and rs11568785 is located Selleck RXDX-106 850 bp downstream of exonn 5 and 1.18 kb upstream of exonn 6. These results are consistent with our earlier findings as each of these SNPs was significantly
associated with TGFBR1 ASE in our original study. PLX4032 For example, in this study six (54.5%) of the 11 patients with TGFBR1 ASE carried the TGFBR1*6A allele. In our previous report 14 (48.3%) of the 29 patients with TGFBR1 ASE carried the TGFBR1*6A allele. This provides additional evidence of a central role for TGFBR1*6A in colorectal cancer, especially as it relates to the TGFBR1 ASE phenotype. Studies are currently in progress to validate the association of TGFBR1
SNPs with colorectal cancer risk. Table 2 Association of TGFBR1 SNPs with constitutively decreased TGFBR1 allelic expression (TGFBR1 ASE). Frequency Allele 2 SNP ASE < 0.67 or > 1.5 1.5 > ASE > 0.67 P OR rs4742761 0.14 0.25 0.38 0.5 rs2416666 0.19 0.19 0.98 1.0 rs7874183 0.13 0.28 0.20 0.4 rs7034462 0.31 0.05 7.2 × 10-4 8.3 rs10819634 0.06 0.26 0.08 0.2 rs1888223 0.50 0.30 0.11 2.3 9A/6A 0.31 0.04 1.6 × 10-4 10.9 rs10988705 0.00 0.04 0.42 n/a rs6478974 0.50 0.47 0.82 1.1 rs10739778 0.38 0.36 0.89 1.1 rs2026811 0.25 0.32 0.57 0.7 rs10512263 0.00 0.11 0.16 n/a rs11568785 0.25 0.02 1.4 × 10-4 16.0 rs334348 0.31 0.39 0.55 0.7 rs7871490 Amobarbital 0.50 0.46 0.77 1.2 rs334349 0.25 0.43 0.19 0.5 rs7850895 0.07 0.06 0.87 1.2 rs1590 0.25 0.39 0.28 0.5 rs1626340 0.25 0.32 0.57 0.7 Discussion These findings confirm the relatively high frequency of the TGFBR1 ASE phenotype in patients with colorectal cancer. The phenotype frequency among Caucasian patients included in this study (10.2%) is similar to that of the Caucasian patients studied in our earlier report (12.0%)[14]. Intriguingly, Guda et al.