类核沉降法对三个着色性干皮病(XP)家系成员DNA修复能力的测定及杂合子的检出

DNA Repair Capacity Measurement and Possibility of Heterozyg-ote Detection Using Nucleoid Sedimentation Technique Among Members Taken from 3 Xeroderma Pigmentosum (XP) Families

应用类核沉降法,分析了三个着色性干皮病家系中35名成员外周血淋巴细胞在紫外线(2.5μJ/mm^2)照射和MNNG(2μg/mI)损伤后DNA修复能力。结果表明,6名XP患者和9名杂合子DNA损伤后20小时尚不能完成修复,他们11小时DNA修复率均值分别为UV,0.61±0.13,0.59±0.15和MNNG,0.44±0.15,0.46±0.16,与家系中10名非血缘亲属正常人DNA修复率均值为UV,0.96±0.07,MNNG,0.71±0.07相比,差异非常显著(Ρ<0.01),而XP患者和杂合子DNA修复率则无显著性差异(Γ>0.05)。提示,类核沉降技术可能为XP家系中杂合子成员检出提供一种有希望的方法。

The nucleoid sedimentation test was used to analyse the DNA repair capacity in 35 members taken from 3 xeroderma pigmentosum (XP) families after their peripheral blood lymphocytes being exposed to UV irradiation or N-methyl-N-nitro-N-nitrosoguanidine (MNNG) at a dose of 2.5μJ/mm2 and 2μg/ml respectivtly. The results showed that the 6 XP patients all failed to repair their damaged DNA even after 20-hour incubation at 37±. The repair ratios were 0.61 ±0.13 for UV and 0.44 ±0.15 for MNNG while those of non-related normal members usually reached 0.96 ±0.07 and 0.71 ±0.07 for both UV and MNNG after 11-hour incubation. It is interesting to note that 9 obligatory heterozygotes (parents and grandparents of XP patients) and 4 highly possible heterozygotes (blood relatives of XP patients) also showed very poor DNA repair capacity: they could not accomplish their repair process even after 20-hour incubation. It has been showed that the nucleoid sedimentation. test can probably be used to pick out the heterozygotes in XP families.