Functional Identification of Genes Mutated in FHLH

描述（由申请人提供）：家族性噬血细胞淋巴组织细胞病（FHLH）几乎是普遍致命的，除非在诊断后立即积极治疗，并通过同种异体骨髓移植纠正。所有形式的FHLH可能是由免疫/炎症反应自然下调机制中的遗传缺陷引起的。三种常染色体隐性基因缺陷是全世界40-50%的原发性（家族）病例的基础：穿孔素（20-30%），主要的免疫细胞毒性蛋白，MUNC 13- 4(20%)，一种参与细胞凋亡过程中携带穿孔素的细胞毒性颗粒胞外分泌的蛋白，STX11，可溶性n-乙基male亚胺敏感因子附着蛋白受体（SNARE）的成员。因此，在一半以上的FHLH病例中，受影响的个体有其他未知的遗传改变。通过连锁分析来识别这些基因的经典遗传方法具有局限性，因为连锁分析通常使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庭数量的不切实际，等位基因频率低，以及患有该疾病的家庭罕见等因素通常会阻止统计缩小这些大区域以确定相关基因。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易感位点的解剖。我们的策略利用RNA干扰（RNAi），双链RNA诱导同源mRNA的同源依赖性降解的过程。RNAi策略将用于鉴定染色体9q21.3-22上淋巴组织细胞病易感性区域的候选基因，以及编码直接、受控和非常快速的磷脂膜融合所必需的SNARE蛋白的基因。公共卫生相关性：家族性噬血细胞淋巴组织病、疾病基因、鉴定、微阵列、无义介导的mRNA衰变、RNA干扰、SNAREs。

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.