GENETIC ASPECTS OF IMMUNODEFICIENCIES

X连锁无丙种球蛋白血症(XLA)是一种单基因缺陷 由于严重的低丙种球蛋白血症和B细胞数量的显著减少 细胞。该异常基因产物尚未被鉴定，但是， PI实验室的研究表明，基因缺陷是 B细胞血统固有的基因产物很可能 在B细胞分化过程中均有表达。在下一次预算中 PI计划识别、分离和表征基因的时间段 XLA.连锁研究已将xla基因定位在6-10 mb。 X染色体的片段。还没有看到重组与 在Xq22处探测p2l2，提示该基因缺陷很可能是 在p2l2的1-2MB范围内。 在第一个具体目标中，PI将使用脉冲场电泳， 酵母人工染色体(YAC)、新的DNA探针和连锁 进一步提纯XLA基因所在DNA片段的分析 一定是在撒谎。在初步研究中，感兴趣的部分是 通过对重组X染色体的分析，将其修剪到2-3mb。这个 两名无血缘关系的男性的细胞和DNA的可用性 XLA基因的缺失应该有助于进一步定位 吉恩。包含XLA基因位点的YAC将被用来生成 新的DNA探针。 在第二个特定目标中，PI将识别B细胞特异性 在XLA基因片段中编码的转录本。甲基化 以上描述的网站将被详细描述。此外, 来自包含XLA基因的重叠YAC的噬菌体文库 将该片段用于筛选B细胞c DNA文库。以特定的目标 三、基因组DNA和/或B细胞系的mRNA来自21个无关的 XLA患者将用识别XLA基因的探针进行分析 候选人。XLA基因Will的鉴定与鉴定 毫无疑问，改善了对受影响患者的诊断和护理。它应该是 也增加了我们对正常B细胞参与机制的理解 差异化。

X-linked agammaglobulinemia (XLA) is a single gene defect characterized by profound hypogammaglobulinemia and markedly reduced numbers of B cells. The abnormal gene product has not yet been identified; however, studies in the Pi's laboratory have shown that the gene defect is intrinsic to the B cell lineage and that the gene product is likely to be expressed throughout B cell differentiation. In the next budget period the PI plans to identify, isolate and characterize the gene for XLA. Linkage studies have localized the gene for XLA to a 6-10 mb segment of the X chromosome. No recombination has been seen with the probe p2l2 at Xq22, suggesting that the gene defect is likely to be within 1-2 mb of p2l2. In the first specific aim, the PI will use pulse field electrophoresis, yeast artificial chromosomes (YACs), new DNA probes and linkage analysis to further refine the DNA segment within which the XLA gene must lie. In preliminary studies, the segment of interest has been trimmed to 2-3 mb by analysis of recombinant X chromosomes. The availability of cells and DNA from two unrelated males who are likely to have deletions of the XLA gene should help further localize the gene. YACs that encompass the XLA gene locus will be used to generate new DNA probes. In the second specific aim, the PI will identify B cell specific transcripts that are encoded in the XLA gene segment. The methylation site described above will be characterized in detail. In addition, phage libraries from overlapping YACs that encompass the XLA gene segment will be used to screen B cell cDNA libraries. In specific aim three, genomic DNA and/or B cell lineage mRNA from 21 unrelated patients with XLA will be analyzed with probes that identify XLA gene candidates. Identification and characterization of the XLA gene will undoubtedly improve diagnosis and care of affected patients. It should also increase our understanding of mechanisms involved in normal B cell differentiation.