The Human Leukocyte Antigen (HLA) has a crucial role in the development and pathogenesis of coeliac disease (CD). The genes HLA-DQA1 and HLA-DQB1, both lying in this region and encoding the HLA-DQ heterodimer, are the main genetic predisposing factors to CD. Approximately 90% of CD patients carry the heterodimer HLA-DQ2.5, leaving only a small proportion of patients with lower risk heterodimers (HLA-DQ8, HLA-DQ2.2 or HLA-DQ7.5). These HLA-DQ molecules act as receptors present in the surface of antigen presenting cells and show high affinity for deamidated gluten peptides, which bind and present to CD4⁺ T cells. This triggers the immunological reaction that evolves into CD. Since specific HLA genetics is present in almost the totality of CD patients, HLA typing has a very high negative predictive value, and it can be used to support diagnosis in specific scenarios. HLA risk has been associated to different CD-related features, such as age at onset, clinical outcomes, antibody levels and grade of histological lesion; but further research is needed. HLA-DQ genotypes have been also suggested to modulate the composition of the gut microbiota.

人类白细胞抗原 (HLA) 在乳糜泻 (CD) 的发展和发病机制中起着至关重要的作用。基因HLA-DQA1和HLA-DQB1都位于该区域并编码 HLA-DQ 异二聚体，是 CD 的主要遗传易感因素。大约 90% 的 CD 患者携带异二聚体 HLA-DQ2.5，只有一小部分患者携带风险较低的异二聚体（HLA-DQ8、HLA-DQ2.2 或 HLA-DQ7.5）。这些 HLA-DQ 分子作为存在于抗原呈递细胞表面的受体，对结合并呈递至 CD4 ^{+的脱酰胺化面筋肽显示出高亲和力}T细胞。这触发了演变成 CD 的免疫反应。由于几乎所有 CD 患者都存在特定的 HLA 遗传学，因此 HLA 分型具有非常高的阴性预测值，可用于支持特定情况下的诊断。HLA 风险与不同的 CD 相关特征相关，例如发病年龄、临床结果、抗体水平和组织学病变等级；但需要进一步研究。HLA-DQ 基因型也被认为可以调节肠道微生物群的组成。