THE ETIOLOGY OF SOMATIC MUTATIONS IN PAROXYSMAL NOCTURNAL HEMOGLOBINURIA (PNH)

阵发性睡眠性血红蛋白尿 (PNH) 体细胞突变的病因学

基本信息

批准号：
11671005
负责人：
KAWAGUCHI Tatsuya
金额：
$ 0.7万
依托单位：
KUMAMOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

PNH is an acquired clonal stem cell disorder characterized by a somatic mutation in the PIG-A gene. Although the molecular mechanism of intravascular hemolysis is well understood, the etiology of PIG-A gene mutation and the mechanism of selective expansion of affected cells still remain unknown. Based on the presence of multiple PIG-A mutations, more than one PIG-A mutant clones in a single patient and a coexistence with MDS or leukemia clones in some patients, we hypothesize the genetic instability in the overeall genome in PNH.To test this, three distinct markers of genetic instability, microsatellite instability (MSI), chromosomal abnormality and mutation rate of the hypoxanthine-guanine phosphoribosyl-transferase (HPRT) gene were analyzed in PNH patients.We first examined MSI in 20 patients and found rarity of MSI as reported (Eur J Haematol, 64 : 430-2, 2000).To asses the chromosomal instability, aneuploidy for chromosome 7 and 8 was analyzed in 13 patients using G-banding and fluorescence in situ hybridization (FISH). Five (38%) had monosomy 7(-7) but none had trisomy 8, suggesting not only that chromosome 7 is genetically unstable in PNH but also that -7 is a useful marker for monitoring the disease progression to MDS or leukemia.Using HPRT gene mutation assay combined with T cell colony formation, we examined the frequency of mutations in T cell colonies. Mutant colonies were found in 8 of 12 (67%) patients and 3 of 17 (l8%) age-matched health volunteers (p<0.02). The incidence of mutant colonies was extremely higher in the patients (mean 84, x10^<-6>) than in the healthy donors (mean 1.3, x10^<-6>). Thus, the HPRT gene mutate more frequently in patients with PNH than in healthy controls.Taken together, we concluded that in PNH patients, conditions exist that favor the occurrence of diverse somatic mutations in blood cells.

PNH 是一种获得性克隆干细胞疾病，其特征是 PIG-A 基因体细胞突变。尽管血管内溶血的分子机制已被充分了解，但 PIG-A 基因突变的病因和受影响细胞选择性扩增的机制仍不清楚。基于多个 PIG-A 突变的存在、单个患者中存在多个 PIG-A 突变克隆以及某些患者中与 MDS 或白血病克隆共存，我们假设 PNH 的整体基因组中存在遗传不稳定性。，遗传不稳定性、微卫星不稳定性（MSI）、染色体异常和次黄嘌呤鸟嘌呤磷酸核糖基转移酶（HPRT）基因突变率的三个不同标记是我们首先检查了 20 名患者的 MSI，发现 MSI 的罕见性如报道的那样（Eur J Haematol，64：430-2，2000）。为了评估染色体不稳定性，对 13 名患者的 7 号和 8 号染色体的非整倍性进行了分析使用 G 带和荧光原位杂交 (FISH)。 5 例 (38%) 具有 7(-7) 单体，但没有人具有 8 三体，这表明不仅 PNH 中 7 号染色体在遗传上不稳定，而且 -7 是监测疾病进展为 MDS 或白血病的有用标记。使用 HPRT基因突变检测结合T细胞集落形成，我们检查了T细胞集落的突变频率。在 12 名患者中的 8 名 (67%) 和 17 名年龄匹配的健康志愿者中的 3 名 (18%) 中发现了突变菌落 (p<0.02)。患者中突变菌落的发生率(平均84，x10^-6)远高于健康供体(平均1.3，x10^-6)。因此，PNH 患者的 HPRT 基因突变比健康对照者更频繁。综上所述，我们得出的结论是，在 PNH 患者中，存在有利于血细胞中发生多种体细胞突变的条件。