颅内海绵状血管畸形CCM1基因突变的分析

目的探讨颅内海绵状血管畸形（ICM）患者CCM1基因突变的情况。方法收集经手术病理证实的ICM患者25例，均为汉族，其中家族性ICM7例。以30例正常健康人作为对照组。抽取两组对象的静脉血，提取基因组DNA、PCR，扩增CCM1基因8、9、11、12、13、15、16、17、18号外显子及部分两侧相邻的内含子、DNA测序，结果与GenBank比较。结果ICM患者中有11例被检测出7个新的CCM1基因突变，突变率为44％（11／25）。其中错义突变3个：12号外显子，1160A→C（Q387P）、1172C→T（S391F）；13号外显子，1405A→C（N469H），插入突变2个：8号外显子，704insT（K246stop）；18号外显子，2138insG（T733stop），内含子突变1个：IVS12-4C→T，同义突变1个：17号外显子，1875C→T（F625F）。除了1875C→T的同义突变可能为基因多态性以外，其他被发现的CCM1基因突变均导致编码KRIT蛋白的变化。对照组的CCM基因未检测出异常。家族性ICM的CCM1基因突变率高于散发性ICM，两者比较差异有统计学意义（P〈0．05）。结论国人ICM患者同样存在CCM1基因的突变，导致编码的KRIT1蛋白功能改变或缺失，这与ICM发病相关，是ICM发病的遗传学基础。

Analysis of CCM1 gene mutations in Chinese patients with intracranial cavernous malformations

OBJECTIVE: To study the CCM1 gene (7q11.2 - q22) mutations in Chinese patients with intracranial cavernous malformations (ICM), METHODS: Peripheral blood samples were collected from 25 unrelated patients with ICM confirmed by post-operational pathology, 7 being with familial ICM, all of Han nationality, and from 30 healthy people as controls. The genomic DNA was extracted and the exons 8, 9, 11, 12, 13, 15, 16, 17, and 18 of CCM1 gene and part of intervening sequences near both sides of these exons were amplified by PCR. The PCR products were sequenced directly and then compared with the GenBank data. RESULTS: Seven new mutation sites of CCM1 gene were detected from 11 Chinese ICM patients with a total mutation rate of 44%. Of the seven new mutations there were three missense mutations: 1160A-->C (Q387P) and 1172C-->T (S391F) in exon12, and 1405A-->C (N469H) in exon13; two insertion mutations: 704insT (K246stop) in exon8, and 2138insG (T733stop) in exon18; one intervening sequence mutation: IVS12 - 4C-->T; and one synonymous mutation: 1875C-->T (F625F) in exon17. None mutation was detected in the control group. The CCM1 mutation rate of familial ICM was 85.7%, significantly higher than that of sporadic ICM (27.7%, P < 0.05). CONCLUSION: As the genetic basis of ICM, CCM1 gene mutation exists in Chinese ICM patients too, that leads to functional loss or changes of the gene encoding KRIT1 protein.