Studies of linkage disequilibrium across the HLA class II region have been useful in predicting where recombination is most likely to occur. The strong associations between genes within the 85-kb region from DQB1 to DRB1 are consistent with low frequency of recombination in this segment of DNA. Conversely, a lack of association between alleles of TAP1 and TAP2 (approximately 15 kb) has been observed, suggesting that recombination occurs here with relatively high frequency. Much of the HLA class II region has now been sequenced, providing the tools to undertake detailed analysis of recombination. Twenty-seven families containing one or two recombinant chromosomes within the 500-kb interval between the DPB1 and DRB1 genes were used to determine patterns of recombination across this region. SSCP analysis and microsatellite typing yielded identification of 127 novel polymorphic markers distributed throughout the class II region, allowing refinement of the site of crossover in 30 class II recombinant chromosomes. The three regions where recombination was observed most frequently are as follows: the 45-kb interval between HLA-DNA and RING3 (11 cases), the 50-kb interval between DQB3 and DQB1 (6 cases), and an 8.8-kb segment of the TAP2 gene (3 cases). Six of the 10 remaining recombinants await further characterization, pending identification of additional informative markers, while four recombinants were localized to other intervals (outliers). Analysis of association between markers flanking HLA-DNA to RING3 (45 kb), as well as TAP1 to TAP2 (15 kb), by use of independent CEPH haplotypes indicated little or no linkage disequilibrium, supporting the familial recombination data. A notable sequence motif located within a region associated with increased rates of recombination consisted of a (TGGA)12 tandem repeat within the TAP2 gene.

中文翻译：

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HLA II类区域中重组的特征。

跨HLA II类区域的连锁不平衡研究对于预测最可能发生重组的位置很有用。从DQB1到DRB1的85 kb区域内的基因之间的强关联与DNA片段中重组的低频率一致。相反，已经观察到TAP1和TAP2的等位基因之间缺乏关联（约15kb），这表明此处重组发生的频率较高。现在已对HLA II类区域的大部分进行了测序，从而提供了进行重组详细分析的工具。二十七个家族包含一个或两个在DPB1和DRB1基因之间的500 kb间隔内的重组染色体，用于确定该区域的重组模式。SSCP分析和微卫星分型鉴定了分布在整个II类区域的127个新的多态性标记，从而可以优化30个II类重组染色体中的交换位点。最常观察到重组的三个区域如下：HLA-DNA与RING3之间的45 kb间隔（11例），DQB3与DQB1之间的50 kb间隔（6例）和8.8kb的TAP2基因（3例）。其余10个重组体中有6个等待进一步鉴定，尚待鉴定其他信息标记，而4个重组体则定位在其他区间（异常值）。通过使用独立的CEPH单倍型分析HLA-DNA与RING3（45 kb）以及TAP1与TAP2（15 kb）两侧的标记之间的关联，表明很少或没有连锁不平衡，支持家族重组数据。位于与重组率增加相关的区域内的显着序列基序由TAP2基因内的（TGGA）12串联重复序列组成。