两个Ⅱ型神经纤维瘤病家系的临床表现及其与NF2基因突变的关系

Mutation analysis of NF2 gene and clinical investigation in two families with neurofibromatosis type Ⅱ

摘要:

目的 报告两个Ⅱ型神经纤维瘤病家系的NF2基因突变，并探讨基因型与表型的关系。方法 提取两个家系中的先证者或先证者之子及其家族成员与100名无血缘关系的健康对照者的血液DNA，对先证者的NF2基因的15个外显子（从外显子1到15）及邻近的内含子序列进行聚合酶链反应（PCR），使用直接测序的方法对PCR产物进行检测；对家系1的家族成员内含子2剪接供体处进行PCR及测序；对家系2的家族成员内含子7剪接受体处进行PCR及测序；对100名无血缘关系的健康对照者的内含子2剪接供体和内含子7剪接受体处进行PCR及测序。结果 家系1中先证者及其余患者中均存在内含子2剪接供体位点g>t的突变。家系2中患者存在内含子7剪接受体位点a>g的突变。家系中未患病者及对照者中无此突变，并排除了2个位点基因多变性的可能性。结论 家系1和2中存在的剪接位点突变，导致了mRNA的剪接异常，影响了Merlin蛋白的生物学功能，使其失去对正常神经细胞生长的调控，进而导致了神经纤维瘤病的发生。

Abstract:

Objective To report mutations of neurofibromatosis 2 (NF2) gene in 2 families of NF2 and investigate the genotype-phenotype correlations. Methods The blood DNA samples of the probands or their sons and theirs family members in 2 families with NF2 and 100 healthy controls without kinship were extracted. Polymerase chain reaction (PCR) was performed on 15 exons (exons 1~15) and adjacent intron sequences of the NF2 gene of the probands, and the PCR products were detected by direct sequencing. PCR and sequencing were performed at splice donor site of intron 2 in members of family 1, and splice receptor site of intron 7 in family 2, as well as both the splice donor site of intron 2 and receptor site of intron 7 in the controls. Results Mutation of intron 2 splice donor site g>t was found in the proband and other patients in family 1. Mutation of intron 7 splice receptor site a>g was found in patient in family 2. There were no such mutations in the unaffected or control ones and the possibility of gene variability at both sites was ruled out. Conclusion Splice site mutations in lineages 1 and 2 lead to abnormal mRNA splicing, which affect the biological function of Merlin protein to lose its control over the growth of normal nerve cells and lead to development of neurofibromatosis.