JCEM-jc-2019-01933-FROMMER-SUPPLEMENTAL_MATERIAL

<br><b>Context</b>: The structure of the human leucocyte antigen (HLA) peptide-binding clefts strongly contributes to monoglandular and polyglandular autoimmunity (AP). <br><b>Objective</b>: To investigate the impact of amino acid polymorphisms on the peptide binding interactions within HLA class II and its association with AP <br><b>Design: </b>immunogenetic study <br><b>Setting</b>: Tertiary referral center for autoimmune endocrine diseases <br><b>Subjects</b>: 587 subjects with AP, autoimmune thyroid disease (AITD), type 1 diabetes (T1D) and healthy unrelated controls were typed for HLA class II. <br><b>Methods: </b>Amino acids within the peptide binding cleft that are encoded by HLA class II exon 2 were listed for all codon positions in all subjects. Overall comparisons between disease and control groups with respect to allele distribution at a given locus were performed by assembling rare alleles applying an exact Freeman Halton contingency table test with Monte-Carlo p values based on 150,000 samples. <br><b>Results</b>: The Montecarlo Exact Fisher Test demonstrated marked differences in all three Loci, <i>DQA1</i>, <i>DQB1</i>, <i>DRB1</i> (p&lt;0.0001) between AP versus both AITD and controls, as well as between AP type II (Addison’s disease as major endocrine component) and AP type III (T1D + AITD). Differences were also noted between AP and T1D pertaining to the <i>DRB1</i> allele (p&lt;0.041). The following seven amino acid positions DRB1-13, DRB1-26, DRB1-71, DRB1-74, DQA1-47, DQA1-56, and DQB1-57 significantly contributed to AP. Five positions in <i>DQA1</i> (11, 47, 50, 56, and 69) completely correlated (p&lt;0.0001). <br><b>Conclusion</b>: Amino acid polymorphisms within HLA class II exon 2 mediate the AP risk and differentiate between thyroid and polyglandular autoimmunity. <br>

<b>背景</b>：人类白细胞抗原（HLA）肽结合槽的结构与单腺体及多腺体自身免疫病（AP）的发生密切相关。<br><b>研究目的</b>：探讨氨基酸多态性对HLA II类分子肽结合相互作用的影响，及其与AP的关联。<br><b>研究设计</b>：免疫遗传学研究<br><b>研究场景</b>：自身免疫性内分泌疾病三级转诊中心<br><b>研究对象</b>：共纳入587名受试者，包括AP患者、自身免疫性甲状腺病（AITD）患者、1型糖尿病（T1D）患者及健康无关对照，均完成HLA II类基因分型。<br><b>研究方法</b>：对所有受试者的所有密码子位点，均列出由HLA II类外显子2编码的肽结合槽内的氨基酸。针对特定基因座的等位基因分布，通过合并稀有等位基因，采用基于150000次抽样的蒙特卡洛（Monte-Carlo）p值的精确Freeman-Halton列联表检验，开展疾病组与对照组的整体比较。<br><b>研究结果</b>：蒙特卡洛精确费希尔检验显示，在AP与AITD、健康对照的组间比较，以及II型AP（以艾迪生病为主要内分泌受累表现）与III型AP（T1D合并AITD）的组间比较中，DQA1、DQB1、DRB1三个基因座均存在显著差异（p<0.0001）。AP与T1D在DRB1等位基因分布上亦存在显著差异（p<0.041）。以下7个氨基酸位点与AP的发生显著相关：DRB1-13、DRB1-26、DRB1-71、DRB1-74、DQA1-47、DQA1-56及DQB1-57。DQA1基因座的5个位点（11、47、50、56及69）呈现完全相关性（p<0.0001）。<br><b>研究结论</b>：HLA II类外显子2内的氨基酸多态性可介导AP的发病风险，并可区分甲状腺源性自身免疫病与多腺体自身免疫病。