Table 1. Frequency of DRD4-VNTR genotypes regarding presence or absence of 7R allele and rare variants and respective estimated odds ratios (OR) for high hyperactivity and inattention scores.
| Model | Genotype | Low-score group n (%)A | High-score group n (%)A | OR (95% CI) | P-valueD |
|---|---|---|---|---|---|
| VNTR allele length | 7R carriers | 1,047 (35.8%) | 122 (36.0%) | 1.029 (0.812-1.302)B | 0.815 |
| Others | 1,879 (64.2%) | 217 (64%) | 1 | -- | |
| Sequences - Model 1 (Synonymous and non-synonymous included) | Presence of at least 1 copy of 4R rare variant | 77 (15.0%) | 14 (21.0%) | 1.790 (0.901-3.557)C | 0.096 |
| Presence of at least 1 copy of 7R rare variant | 38 (7.4%) | 9 (13.4%) | 2.561 (1.133-5.790)C | 0.024 | |
| Common variants | 398 (77.6%) | 44 (65.6%) | 1 | -- | |
| Sequences - Model 2 (Only non-synonymous included) | Presence of at least 1 copy of 4R rare protein variant | 61 (11.9%) | 10 (14.9%) | 1.593 (0.740-3.428)C | 0.234 |
| Presence of at least 1 copy of 7R rare protein variant | 30 (5.8%) | 8 (11.9%) | 3.216 (1.348-7.671)C | 0.008 | |
| Common variants | 422 (82.3%) | 49 (73.2%) | 1 | -- |
A The analysis considering VNTR allele length comprised a sample size of 3,265 subjects (2,926 in low-score group and 339 in high-score group) while the analysis with the sequences comprised 580 subjects (513 in in low-score group and 67 in high-score group);
B Logistic regression adjusted for gender and ethnicity;
C Logistic regression adjusted for gender, ethnicity and alcohol consumption during pregnancy;
D Significance level at 0.05