摘要
目的分析电压门控钾离子通道基因KCNQ2与1个良性家族性婴儿惊厥(benign familial infantile convulsions,BFIC)家系的关系,探讨BFIC的分子遗传机制。方法1个中国陕西地区4代BFIC家系,采集41名家系成员及家系外75名健康对照的血样,采用PCR扩增、DNA直接测序技术进行KCNQ2基因突变分析,采用多聚酶链反应-单链构象多态性进行基因型和表型共分离研究。结果PCR-DNA直接测序在先证者第5号外显子发现KCNQ2基因杂合突变G812T,导致KCNQ2蛋白孔区一个甘氨酸被缬氨酸替代(G271 V),这个位置的甘氨酸在KCNQ家族进化上高度保守。此突变与以前发现的良性家族性新生儿惊厥(benign familial neonatal convulsion,BFNC)家系KCNQ3突变(G310V)是同一位置相同的氨基酸改变。家系中其他患儿均检出与先证者相同的突变,而家系内参加本研究的健康人和家系外75名健康对照未出现这种突变。结论KCNQ2基因突变可能是部分BFIC的分子发病机制,KCNQ2基因G812T突变是国内外未曾报道过的新突变,进一步开展G812T突变的功能研究有助于理解BFIC及其他原发性癫癎的分子发病机理。
Objective Benign familial infantile convulsions （BFIC） is a form of idiopathic epileptic syndrome characterized by onset of afebrile seizures between 3 and 12 months of life, Spontaneous remission after several weeks or months, and autosomal dominant mode of inheritance. Previous linkage analysis in western countries defined three susceptible loci on chromosomes 19q12.0-13.1, 16p12-q12, and 2q23-31, but studies performed in several Chinese families with BFIC got negative results of these previously reported loci. The authors investigated the relation of voltage-gated potassium channel gene KCNQ2 to BFIC in a Chinese family and thus to understand the molecular pathogenesis of BFIC. Methods A four-generation Chinese BFIC family was investigated. All the affected 17 members had similar pattern of seizures starting from 2 to 6 months of age. In 15 of them, the seizures disappeared spontaneously within the first year of life. The phenotype extended beyond infancy only in two patients. Blood sample was collected from the 41 family members and 75 unassociated normal individuals. Polymerase chain reaction （PCR）-DNA direct sequencing was performed to screen all exons and their flanking introns of KCNQ2 gene for mutation analysis. Polymerase chain reaction-single strand conformation polymorphism （PCR-SSCP） was used to ascertain the co-segregation of genotype and phenotype and to exclude polymorphism. Results PCR amplification and subsequent direct sequencing of KCNQ2 from the DNA of proband revealed a heterozygous guanine to thymine nucleotide exchange （G812T） in exon 5, leading to the substitution of glycine by valine at amino acid position 271 （G271V） of the predicted protein. The same mutation with a comparable localization has been previously described for KCNQ3 in benign familial neonatal convulsions （BFNC）. The glycine at this position （ G271 ） is located in pore region of KCNQ2 protein and is evolutionarily highly conserved. The same SSCP variant as that of the proband was shown in the rest of the affected members of this family but not in the unaffected members enrolled in the study of this family and all the 75 unrelated normal individuals. Conclusion Previously reported mutations of KCNQ2 were mainly identified in BFNC family in which at least one individual had an onset of seizures during the first week of life, a hallmark of the BFNC disorder. The results of the present study suggest the possibility that KCNQ2 mutation exist in patients with BFIC diagnosis. GS12T of KCNQ2 gene is a novel mutation found in BFIC and functional expression of KCNQ2 G812T is required for understanding the mechanism of BFIC and other idiopathic epilepsy.
出处
《中华儿科杂志》
CAS
CSCD
北大核心
2006年第7期487-491,共5页
Chinese Journal of Pediatrics
关键词
癫痫
正常新生儿
钾通道
突变
系谱
Epilepsy, benign neonatal
Potassium channels
Mutation
Pedigree
作者简介
通信作者：马爱群
