Table 3.
Association between MTHFR C677T and A1298C genotypes and distal adenoma risk, for the total study population, by dietary folate and alcohol
| Genotype | 528–2,191 mcg/daya,b | 360–527 mcg/day | 262–359 mcg/day | 42–261 mcg/day | p Trend | p Heterogeneity |
|---|---|---|---|---|---|---|
| Dietary folate quartiles | ||||||
| 677TT/677CC + CT c | ||||||
| CC + CT: cases/controls | 124/145 | 127/149 | 122/152 | 187/144 | 0.70 | 0.12 |
| TT: cases/controls | 14/20 | 13/24 | 24/15 | 17/18 | ||
| OR (95% CI)d | 0.91 (0.44, 1.9) | 0.66 (0.32, 1.36) | 2.01 (1.0, 4.05) | 0.78 (0.39, 1.6) | ||
| 1298CC/1298AA + AC | ||||||
| AA + AC: cases/controls | 125/158 | 127/157 | 152/157 | 195/162 | 0.12 | 0.004 |
| CC: cases/controls | 14/20 | 13/24 | 24/15 | 17/18 | ||
| OR (95% CI) | 2.07 (0.92, 4.6) | 1.15 (0.57, 2.33) | 0.22 (0.07, 0.65) | 1.27 (0.57, 2.85) | ||
| 0 g/daye | 0.1–10 g/day | 11–20 g/day | >20–600 g/day | p Trend | p Heterogeneity | |
|---|---|---|---|---|---|---|
| Alcohol use | ||||||
| 677TT/677CC + CT | ||||||
| CC + CT: cases/controls | 265/277 | 153/196 | 60/50 | 80/67 | 0.52 | 0.68 |
| TT: cases/controls | 26/30 | 18/29 | 8/9 | 16/9 | ||
| OR (95% CI) | 0.96 (0.55, 1.68) | 0.83 (0.44, 1.56) | 0.69 (0.24, 1.93) | 1.46 (0.60, 3.55) | ||
| 1298CC/1298AA + AC | ||||||
| AA + AC: cases/controls | 278/297 | 163/210 | 63/53 | 94/74 | 0.94 | 0.98 |
| CC: cases/controls | 24/28 | 18/23 | 8/6 | 4/4 | ||
| OR (95% CI) | 0.92 (0.52, 1.64) | 1.11 (0.57,2.13) | 1.04 (0.33, 3.25) | 0.88 (0.21, 3.67) | ||
aQuartile cutpoints were based on the distribution of the controls and were study phase specific
bDietary folate values reflect reported average intake in the year before the sigmoidoscopy
cNumbers do not add up to total due to missing values for genotype for some whose race/ethnic group classification was ‘other’ (27 cases/29 controls for C677T and 2 cases/1 control for A1298C) or alcohol (1 case)
dAll ORs and 95% confidence intervals were estimated by unconditional logistic regression assuming a recessive model and adjusting for the matching factors (age, sex, clinic, examination date), race/ethnic group and study phase
eAlcohol cutpoint values were pre-determined and not based on the population distribution of alcohol consumption