GENETIC ASPECTS OF IMMUNODEFICIENCIES

X连锁无丙种球蛋白血症（XLA）是一种单基因缺陷， 严重的低丙种球蛋白血症和B 细胞 异常基因产物尚未被鉴定;然而， Pi实验室的研究表明， 该基因产物可能是B细胞谱系固有的， 在整个B细胞分化过程中表达。 在下一个预算 PI计划识别、分离和表征基因的时间段 XLA 连锁研究已经将XLA的基因定位在6-10 mb的区域， X染色体的一部分。 没有重组已被视为与 探针p2 l2在Xq 22，这表明基因缺陷很可能是 在P2 L2的1-2 MB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（YACs），新的DNA探针和连锁 分析，以进一步完善其中XLA基因的DNA片段， 必须说谎。 在初步研究中， 通过分析重组X染色体修剪至2-3 mb。 的 两个无关的男性的细胞和DNA， 删除XLA基因有助于进一步定位 基因 包含XLA基因座的YAC将用于产生 新的DNA探针 在第二个具体目标中，PI将鉴定B细胞特异性 在XLA基因片段中编码的转录物。 甲基化 将详细描述上述位点的特征。 此外，本发明还提供了一种方法， 来自包含XLA基因的重叠YAC的噬菌体文库 片段将用于筛选B细胞cDNA文库。 具体目标 三，基因组DNA和/或B细胞谱系mRNA从21无关 将用识别XLA基因的探针分析XLA患者 候选人 XLA基因的鉴定和表征将 无疑改善了对受影响患者的诊断和护理。 应当 也增加了我们对正常B细胞 分化

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.