Diagnosis of xeroderma pigmentosum patients and carriers by PCR-RFLP analysis

最近已克隆了A组着色性干皮病（xeroderma pigmentosum，XP）的致病基因XPA。此前的研究表明，大多数日本XPA患者的XPA基因内含子3的剪接位点存在纯合突变，该位点被限制性内切酶（RE）AlwNI识别（AlwNI突变）。其他数据中发现的突变是外显子6中密码子228处的无义突变，由RE HphI识别（HphI突变），以及外显子3中密码子116处的无义突变，由RE MseI识别（MseI突变）。采用聚合酶链反应-限制性片段长度多态性（PCR-PFLP）分析，我们研究了XPA基因的点突变。(1)我们发现17例患者中有12例为AlwNI突变纯合子，4例为AlwNI突变和HphI突变的复合杂合子，1例为AlwNI突变和MseI突变的复合杂合子。对4例HphI基因突变患者的临床特征进行分析， ...更多信息 临床表现较轻。对XPA患者的三个无症状兄弟姐妹的XPA基因的PCR-RFLP分析显示，两个是突变XPA等位基因的携带者，一个不是携带者。(2)我们发现两个兄弟姐妹XP组A显示出显着差异的临床表现和妹妹轻得多。姐姐在4岁时开始严格的防晒，而妹妹在2岁时开始。PCR-RFLP分析显示两例患者均存在XPA基因突变。这些数据表明，XP患者越早开始防晒，皮肤癌的发展就越晚。(3)我们诊断了一个胎儿的XPA基因突变，其兄弟姐妹是一个XPA患者。羊水DNA PCR-RFLP分析显示突变为纯合突变。(4)P53蛋白在DNA损伤修复、细胞周期和凋亡中起重要作用。用蛋白质印迹分析检测UVB对不同基因突变的XPA细胞中p53蛋白的诱导作用。UVB对HphI/AlwNI杂合突变的细胞p53蛋白的诱导作用弱于AlwNI纯合突变或AlwNI/MseI杂合突变的细胞。少

The gene responsible for xeroderma pigmentosum (XP) group A has recently been cloned and designated XPA gene. Previous studies have shown that most Japanese XPA patients have homozygous mutations for the splicing site of intron 3 of the XPA gene, which was recognized by restriction endonuculease (RE) AlwNI (AlwNI mutation). Other mutations found to data have been the nonsense mutation at codon 228 in exon 6, recognized by RE HphI (HphI mutation), and at codon 116 in exon 3, recognized by RE MseI (MseI mutation) . Using polymerase chain reaction restriction fragment length polymorphism (PCR-PFLP) analysis, we examined the point mutations of the XPA gene.(1) We found that 12 patients of 17 patients were homozygous for the AlwNI mutation, four were compound heterozygotes for the AlwNI mutation and the HphI mutation, and one was a compound heterozygote for the AlwNI mutation and the MseI mutation. Investigation of their clinical features suggested that the four patients with HphI mutation … More had milder clinical manifestations. PCR-RFLP analysis of the XPA gene in the three asymptomatic siblings of the XPA patients revealed that two were carriers of the mutated XPA allele, and one was not a carrier.(2) We found two siblings with XP group A who showed a significant difference in clinical manifestations and younger sister was much milder. The elder sister started strict sun protection at 4 years of age, whereas the younger began at 2 years of age. PCR-RFLP analysis revealed that both patients had the identical mutation in XPA gane. These data suggent, that in patients with XP the earlier sun protection begins had the later skin cancer develops.(3) We diagnosed the XPA gene mutation of a fetus whose sibling is a XPA patient. PCR-RFLP analysis of DNA from amniotic fluid showed the homozygous mutation.(4) P53 protein is critical for DNA damage repair, cell cycle and apoptosis. The p53 protein induction by UVB in XPA cells with various gene mutations was examined using western blot analysis. Cells with HphI/AlwNI heterozygous mutations showed weaker induction of p53 protein by UVB than cells with AlwNI homozygous mutations or AlwNI/MseI heterozygous mutations. Less