Identification of Genes Involved in FHLH

描述（申请人提供）：家族性噬血细胞性巨噬组织细胞增多症（FHLH）几乎普遍致命，除非在诊断后立即积极治疗，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/炎症反应的天然下调机制中的遗传缺陷引起的。全世界40-50%的原发性（家族性）病例的基础是三种常染色体隐性基因缺陷：穿孔素（20-30%），主要的免疫细胞毒性蛋白，MMP 13-4（20%），一种在细胞凋亡过程中参与穿孔素细胞毒性颗粒胞吐作用的蛋白，以及STX 11，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。因此，在超过一半的FHLH病例中，受影响的个体具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学方法具有局限性，因为连锁分析需要来自单个家族中相对大量的受影响和未受影响的成员的DNA。这样的家庭在北美并不常见。我们估计至少有六到七个基因可能与FHLH的各种遗传形式有关。在这项研究中，我们提出了新的程序，寻找候选基因负责其余50-60%的FHLH的情况下。据估计，30%的人类遗传性疾病是由提前终止密码子突变引起的。mRNA中的无义突变激活无义介导的衰变（NMD）途径，这导致突变mRNA的降解。我们将确定基因表达谱，将区分FHLH 2，FHLH 3和FHLH 4从其他遗传形式的FHLH。我们认为，NMD通路可用于FHLH候选基因的表达微阵列杂交。此外，候选基因可以通过抑制HVS永生化CD 8 +T细胞中的无义介导的衰变（NMD）机制来鉴定，这些细胞来自遗传原因未知的FHLH患者。或者，我们将使用RNA干扰策略来识别染色体9q21.3-22和11 q25的淋巴组织细胞增多症易感区域中的候选基因，以及编码对于磷脂膜的直接、受控和非常快速的融合至关重要的SNARE蛋白的基因。

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 requires DNA from relatively large numbers of affected and unaffected members of a single family. Such families are unusual in North America. We estimate at least six or seven genes could be responsible to the various genetic forms of FHLH. In this study we propose novel procedures, to search for candidate genes responsible for the remaining 50-60% of FHLH cases. It is estimated that 30% of inherited genetic disorders in humans result from premature termination codon mutations. Nonsense mutations in mRNA activate the nonsense-mediated decay (NMD) pathway, which results in the degradation the mutant mRNA. We will identify gene expression profiles that will distinguish FHLH2, FHLH3 and FHLH4 from other genetic forms of FHLH. We propose that NMD pathway could be utilized to identify FHLH candidate genes through expression microarray hybridization. In addition, candidate genes could be identified through inhibition of the nonsense-mediated decay (NMD) mechanism in HVS immortalized CD8+T cells from patients with FHLH of yet unknown genetic cause. Alternatively, we will use RNAinterference strategy to identify candidate genes in lymphohistiocytosis susceptibility regions of chromosome 9q21.3-22 and 11q25 and among genes coding for SNARE proteins essential for direct, controlled and very rapid fusion of phospholipids membranes.