马凡综合征微纤维蛋白1基因突变检测及单倍型连锁分析

Fibrillin-1 gene mutation in Chinese patients with Marfan syndrome and its gene diagnosis by haplotype analysis

目的 检测中国人马凡综合征 (Marfan syndrome,MFS)患者微纤维蛋白 1(fibrillin- 1,FBN1 )基因的突变及对马凡综合征患者的家系成员进行症状前诊断。方法 应用聚合酶链反应 -单链构象多态性技术和测序方法 ,对汉族 9个家系中共 17个 MFS患者进行基因突变检测 ;运用 FBN1 基因内 4个内含子中的可变串联重复序列构建染色体单倍型 ,进行家系单倍型连锁分析和基因诊断。结果 发现 MFS(A)家系 1 患者有单链构象改变 ,测序证实为位于 FBN1 基因第 2 5号外显子 32 4 3～ 32 5 6核苷酸之间有 1个 13bp的小片段缺失 ,为新位点基因移码突变 ,其序列为 gcctctgcaccca;单倍型连锁分析发现 MFS(B)家系 1 是 1个无症状期患者。结论 中国人 FBN1 基因突变可以引起马凡综合征 。

Objective: To analyze fibrillin-1 (FBN1) gene mutation in Chinese patients with Marfan syndrome (MFS) and to make a gene diagnosis by haplotype analysis for MFS. Methods: Nine MFS families were analysed with single strand conformation polymorphism (SSCP) and DNA sequencing. With the use of four primers designed in the flanking sequences of each short-sequence tandem-repeat region in FBN1 gene, the haplotype-segregation analysis for MFS(B) was performed. Results: In MFS (A) I 1, PCR-SSCP detected SSCP band alterations in exon 25 of FBN1 gene; direct sequencing showed a small 13bp deletion, the deleted sequence being gcctctgcaccca at base 3243-3456 of cDNA. This mutation caused a frame-shift which was never seen in any unaffected members of the family, and it was a heterozygous mutation; neither of them was identified in 100 chromosomes from 50 normal control individuals. Haplotype-segregation analysis suggested that the disease was passed from Subject I2 to Subject I2, Subject II3, Subject II5 with the same allele in MFS (B) family, the proband's daughter also inherited the allele. These data indicated that MFS (B) family was linked to FBN1 gene, the proband's daughter was an asymptomatic patient. Conclusion: The combination of mutation analysis and haplotype analysis can provide more evidence for gene diagnosis.