Table 3 Concordance by HLA‐DR genotype risk group in monozygotic pairs.
| Concordant | Discordant | Total | |
|---|---|---|---|
| Risk genotype group† | |||
| G1 (DR3/3, DR3/7) | 5 | 2 | 7 |
| G2 (DR5/7) | 3 | 3 | 6 |
| G3–G4 (DR3/X, DR4/4, DR4/7, DR7/7) | 8 | 1 | 9 |
| G5 (DR4/Y, DR5/X, DR7/Z) | 1 | 0 | 1 |
| Total | 17 | 6 | 23 |
†HLA grouping is according to relative risks for coeliac disease estimated in the Italian population according to Margaritte‐Jeannin and colleagues.15 DR3 haplotype carries DQB1*0201 and DQA1*0501, DR7 carries DQB1*0202, DR5 carries DQA1*0501, and DR4 carries DQB1*0302.
X = not DR3 or 7; Y = not DR3, 4, or 7; Z = not DR3, 4, 5, or 7.