Novel FBN1 Heterozygous Mutations Identified in Chinese Families with Marfan Syndrome.

Objective: To detect the mutations in the fibronectin-1 gene (FBN1) of four Chinese families with autosomal dominant Marfan syndrome (MFS), and to discuss the associated phenotypes.

Methods: We examined ten patients, and five non-carriers, in four Chinese families with autosomal dominant Marfan syndrome (MFS) for FBN1 mutations. Comprehensive physical, ophthalmic, and cardiovascular examinations were performed on the family members. The FBN1 gene was amplified with PCR from the DNA of the patients and their relatives. The amplified products were sequenced and compared with a reference sequence from the GenBank database. The changes in the structure and function of the protein caused by the amino acid substitution were investigated with a bioinformatics analysis.

Results: In our study, sequencing FBN1 revealed three novel mutations, and one mutation which was found earlier in 2012. One of the novel mutations is c.649T>C in exon 7, which results in the substitution tryptophan by arginine at codon 217 (p.Trp217Arg), the other is a splice defect in intron 39 (c.4816+1G>A), and the third one is c.407G>T in exon 5, which altered an amino acid at residue 136 from Cysteine to Phenylalanine (p.Cys136Phe). The recurrent mutation was c.4151T>C in exon 34, resulting in methionine being replaced by threonine (p.Met1384Thr). The occurrence of the mutations correlated strongly with the phenotypes of the patients, and no mutation was detected in the normal relatives of the affected patients.

Conclusions: In this study, three novel and a recurrent FBN1 mutations were detected. The results expand the mutation spectrum of FBN1, helping in the study of molecular pathogenesis of MFS and Marfan-related disorders.