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

目的：检测中国人马凡综合征（Marfan syndrome,MFS)患者微纤维蛋白1（fibillin-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Ⅱ1患者有单链构象改变，测序证实为位于FBN1基因第25号外显子3243－3256核苷酸之间有I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Ⅲ1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，应用突变检测与单倍型连锁分析方法能为马凡综合征基因诊断提供依据。

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

OBJECTIVE: To analyze fibrillin-1 (FBN(1)) 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 FBN(1) gene, the haplotype-segregation analysis for MFS(B) was performed. RESULTS: In MFS(A)II(1), PCR-SSCP detected SSCP band alterations in exon 25 of FBN(1) 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 I(2) to Subject II(2), Subject II(3), Subject II(5) 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 FBN(1) 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.