Table 2.
Analysis of MC1R and phenotypical traits.
| A. Association of recurrent MC1R with phenotypical traitsB | |||||
|---|---|---|---|---|---|
| Hair colour | Brown/Black | Red | |||
| MC1R Variant | Genotype | N (%) | N (%) | OR ( 95% CI)A | P-value |
| p.R142H | |||||
| G/G | 1168 (97.9) | 58 (78.4) | 1.00 | ||
| G/A | 25 (2.1) | 15 (20.3) | 12.40 (6.18–24.89) | <0.0001C | |
| A/A | 0 (0) | 1 (1.4) | NA | ||
| p.R151C | |||||
| C/C | 1118 (93.7) | 41 (55.4) | 1.00 | ||
| C/T | 75 (6.3) | 28 (37.8) | 10.27 (6.01–17.56) | <0.0001C | |
| T/T | 0 (0) | 5 (6.8) | NA | ||
| p.R160W | |||||
| C/C | 1132 (94.9) | 58 (78.4) | 1.00 | ||
| C/T | 61 (5.1) | 16 (21.6) | 5.2 (2.7–9.4) | <0.0001C | |
| T/T | 0 (0) | 0 (0) | NA | ||
| p.D294H | |||||
| G/G | 1102 (92.4) | 43 (58.1) | 1.00 | ||
| G/C | 91 (7.6) | 25 (33.8) | 6.96 (4.06–11.93) | <0.0001C | |
| C/C | 0 (0) | 6 (8.1) | NA | ||
| Skin phototype | III–IV | I–II | |||
| MC1R Variant | Genotype | N (%) | N (%) | OR ( 95% CI)A | P-value |
| p.R142H | |||||
| G/G | 930 (97.6) | 608 (95.3) | 1.00 | ||
| G/A | 23 (2.4) | 29 (4.5) | 1.95 (1.12–3.41) | 0.027C | |
| A/A | 0 (0) | 1 (0.2) | NA | ||
| p.R151C | |||||
| C/C | 897 (94.1) | 552 (86.5) | 1.00 | ||
| C/T | 55 (5.8) | 79 (12.4) | 2.36 (1.65–3.39) | <0.0001C | |
| T/T | 1 (0.1) | 7 (1.1) | 10.71 (1.31–87.42) | ||
| p.R160W | |||||
| C/C | 906 (95.1) | 584 (91.5) | 1.00 | ||
| C/T | 47 (4.9) | 53 (8.3) | 1.73 (1.15–2.60) | 0.0018C | |
| T/T | 0 (0) | 1 (0.2) | NA | ||
| p.D294H | |||||
| G/G | 883 (92.7) | 553 (86.7) | 1.00 | ||
| G/C | 70 (7.3) | 78 (12.2) | 1.76 (1.25–2.48) | <0.0001C | |
| C/C | 0 (0) | 7 (1.1) | NA | ||
| Eye colour | Dark | Green/Blue | |||
| MC1R Variant | Genotype | N (%) | N (%) | OR ( 95% CI)A | P-value |
| p.R142H | |||||
| G/G | 896 (97.6) | 571 (95.2) | 1.00 | ||
| G/A-A/A | 22 (2.4) | 29 (4.8) | 2.07 (1.18-3-65) | 0.011D | |
| B. Association of number of MC1R variants with phenotypical traits | |||||
|---|---|---|---|---|---|
| Total number of variants | |||||
| 0 Var (%)X | 1 Var (%)X | ≥2 Var (%)X | TOTAL (%) | P-value | |
| Hair colour | |||||
| black/brown | 565 (47.4) | 439 (36.8) | 189 (15.8) | 1193 (100) | |
| red | 4 (5.4) | 12 (16.2) | 58 (78.4) | 74 (100) | <0.0000 |
| Total number of variants | |||||
| 0 Var (%)X | 1 Var (%)X | ≥2 Var (%)X | TOTAL (%) | ||
| Photoype | |||||
| I–II | 219 (34.3) | 235 (36.8) | 184 (28.8) | 638 (100) | |
| III–IV | 472 (49.5) | 338 (35.5) | 143 (15.0) | 953 (100) | <0.0000 |
| Eye colour | |||||
| fair | 268 (44.7) | 207 (34.5) | 125 (20.8) | 600 (100) | |
| dark | 392 (42.7) | 336 (36.6) | 190 (20.7) | 918 (100) | n.s |
| Number of non Red hair colour ( r ) variants | |||||
| 0 Var (%)X | 1 Var (%)X | ≥2 Var (%)X | TOTAL (%) | P-value | |
| Hair colour | |||||
| black/brown | 716 (60) | 392 (32.9) | 85 (7.1) | 1193 (100) | |
| red | 53 (71.6) | 19 (25.7) | 2 (2.7) | 74 (100) | n.s |
| Photoype | |||||
| I–II | 354 (55.5) | 231 (36.2) | 53 (8.3) | 638 (100) | |
| III–IV | 596 (62.5) | 293 (30.7) | 64 (6.7) | 953 (100) | 0.041 |
| Eye colour | |||||
| fair | 361 (60.2) | 199 (33.2) | 40 (6.7) | 600 (100) | |
| dark | 544 (59.3) | 299 (32.6) | 75 (8.2) | 918 (100) | n.s |
| Number of Red hair colour ( R ) variants | |||||
| 0 Var (%)X | 1 Var (%)X | ≥2 Var (%)X | TOTAL (%) | P-value | |
| Hair colour | |||||
| black/brown | 939 (78.7) | 249 (20.9) | 5 (0.4) | 1193 (100) | |
| red | 8 (10.8) | 26 (35.1) | 40 (54.1) | 74 (100) | <0.0000 |
| Photoype | |||||
| I–II | 417 (65.4) | 174 (27.3) | 47 (7.4) | 638 (100) | |
| III–IV | 756 (79.3) | 188 (19.7) | 9 (0.9) | 953 (100) | <0.0000 |
| Eye colour | |||||
| fair | 442 (73.7) | 137 (22.8) | 21 (3.5) | 600 (100) | |
| dark | 680 (74.1) | 205 (22.3) | 33 (3.6) | 918 (100) | n.s |
B
Analysis was performed for each recurrent variant (p.V60L, p.V92M, p.D294H, p.R151C, p.R160W, p.R163Q, p.R142H, p.I155T, p.V122M and p.D84E): Only MC1R variants with statistically significant P-values are shown.
A
ORs are adjusted by age of onset, gender and hospital of recruitment. Model of heritance was chosen according to the AIC and BIC values:
C
:Codominant model;
D
:Dominant model.
X
Number and frequency of patients. NA: not analyzed. n.s: P-values not statistically significant