用双侧DNA探针进行成年型多囊肾病基因诊断的研究

STUDIES ON DIAGNOSIS OF ADULT POLYCYSTIC KIDNEY DISEASE WITH DNA PROBES ON BOTH SIDES OF THE DISEASE GENE

用多囊肾病基因PKD_1的旁侧序列探针24-1与TaqⅠ酶解后69名正常人的DNA杂交,发现了24-1在中国四川地区人群中有B_1和B_2两种等位基因。前者为3.8kb的一个片段,后者为1.5kb和1.3kb的两个片段。B_1、B_2的基因频率分别为0.760和0.240,24-1的多态信息量为0.365。与国外资料比较表明,24-1的等位基因似具有民族或地区特点。联合采用分别位于PKD_1两侧的探针3′HVR和24-1对3个成年型多囊肾病家系进行了基因连锁分析,结果表明:8个家系中有2个家系既与3′HVR连锁,也与24-1连锁,肯定了这两个家系中多囊肾病是由于PKD_1基因异常引起,并对有关的风险成员作了发病前早期诊断。由于使用了双侧探针,对非重组的个体诊断的准确性超过99%。第3个家系与24-1杂交无信息。并对24-1在连锁诊断中的意义和局限性进行了讨论。

The gene responsible for the adult polycystic kidney disease(APKD), PKD_1, has been mapped to the short arm of chromosome 16, and now presymptomatic and prenatal diagnosis can be made by linkage analysis with 3'HVR and other flanking DNA markers. In this study, 241, a flanking single copy polymorphic DNA marker on the other sides of the PKD_1 gene was investigated and was used in combination with 3'HVR for lin- kage analysis of 3 APKD families. Two 24-1 alleles, namely B_1 (3.8kb) and B_2 (1.5kb and 1.3kb) have been found in Chinese population, and the allele frequencies are 78.0% and 24.0% respectively in 69 investigated normal unrelated individuals. The polymorphism information content (PIC) of 24-1 is 0.365. With 3'HVR and 24-1 as bracketing probes, linkage analysis of 3 APKD families was performed, and the presymptomatic DNA diagnosis of the members at risk were made in 2 families. The reliability of the diagnosis, was higher than 99%, which is a significant improvement on the diagnosis with 3'HVR only. In the third family, DNA hybridization with probe 24-1 was noninformative. The usefulness and limitation of 24-1 as a polymorphic DNA marker in diagnosis of APKD were discussed.