Functional Identification of Genes Mutated in FHLH

描述(申请人提供)：家族性噬血细胞性淋巴组织细胞增多症(FHLH)几乎普遍是致命的，除非在确诊后立即积极治疗，并通过异基因骨髓移植纠正。所有形式的FHLH都可能是由于免疫/炎症反应的自然下调机制中的遗传缺陷造成的。在全球40%-50%的原发(家族性)病例中，有三种常染色体隐性基因缺陷：主要的免疫细胞毒蛋白穿孔素(20-30%)，参与细胞毒颗粒在细胞凋亡过程中胞吐的MUNC 13-4(20%)，以及可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体(SNARE)的成员STX11。因此，在超过一半的FHLH病例中，受影响的个体有其他未知的基因改变。通过连锁分析来识别这些基因的经典遗传方法有局限性，因为连锁分析往往会让研究人员面临包含数百个基因的广泛基因组区域。诸如大幅增加测试家系数量的不切实际、低等位基因频率以及患有这种疾病的家系的稀有性等因素往往阻碍了对这些大区域的统计缩小以识别涉及的基因。在这项研究中，我们提出了一种基于细胞生物学的方法来加速FHLH易感基因的分离。我们的策略利用了RNA干扰(RNAi)，这是一个双链RNA诱导同源mRNA同源依赖的降解的过程。RNAi策略将用于确定9q21.3-22染色体上淋巴组织细胞增多症易感区域的候选基因，以及编码SNARE蛋白的基因，这些基因对于磷脂膜的直接、可控和非常快速的融合是必不可少的。公共卫生相关性：家族性噬血细胞淋巴细胞症、疾病基因、鉴定、微阵列、无意义介导的信使核糖核酸衰变、核糖核酸干扰、圈套。

DESCRIPTION (provided by applicant): Familial Hemophagocytic Lymphohistiocytosis (FHLH) is almost universally fatal unless aggressively treated soon after diagnosis, and corrected with allogeneic bone marrow transplantation. All forms of FHLH likely result from genetic defects in the natural down regulating mechanisms of immune/inflammatory responses. Three autosomal recessive gene defects underlie 40-50% of primary (familial) cases worldwide: perforin (20-30%), the major immune cytotoxic protein, MUNC 13- 4 (20%), a protein involved in exocytosis of perforin-bearing cytotoxic granules during apoptosis and STX11, member of soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNARE). Thus in more than half of the FHLH cases, the affected individuals have other as yet unknown genetic alterations. The classic genetic approach to identify these genes, through linkage analysis, has limitations because linkage analysis often leave investigators confronting broad genomic regions containing hundred of genes. Factors such as the impracticality of dramatically increasing the number of families tested, low allelic frequency, and the rarity of families with the disease often prevent the statistical narrowing down of these large regions to identify the involved gene. In this study, we propose a cell-biology-based approach to accelerate the dissection of FHLH susceptibility loci. Our strategy utilizes RNA interference (RNAi), the process where double-stranded RNA induces the homology-dependent degradation of cognate mRNA. The RNAi strategy will be used to identify candidate genes in lymphohistiocytosis susceptibility region on chromosome 9q21.3-22 and among genes coding for SNARE proteins essential for direct, controlled, and very rapid fusion of phospholipids membranes. PUBLIC HEALTH RELEVANCE: Familial Hemophagocytic Lymphohisticytosis, disease genes, identification, microarray, nonsense mediated mRNA decay, RNA interference, SNAREs.