Study On Mutations Of FBN1, TGFBR2 And TGFBR1 Genes In Marfan Syndrome

ObjectiveTo screen mutations in the fibrillin-1(FBN1) gene, Transforming Growth Factor Beta Receptor Typeâ…¡(TGFBR2) gene and Transforming Growth Factor Beta Receptor Typeâ… (TGFBR1) gene from 8 unrelated patients (No.1~No.8) with Marfan syndrome (MFS) and identify the positions and types of these mutations.To observe the relationship between the clinical phenotypes and mutational types of FBN1,TGFBR2 and TGFBR1 genes in Marfan patients.MethodsDenaturing high-performance liquid chromatography (DHPLC)-heteroduplex analysis was introduced to screen for FBN1,TGFBR2 and TGFBR1 mutations exon-by-exon from 8 patients (No1~No8).The DNA amplification fragments which DHPLC elution profiles showed difference from the corresponding normal elution profile were sequenced to identify the position and types of mutations. Blood samples from 50 healthy persons was collected for control of DHPLC.Results1.We screened 8 unrelated patients with MFS and detected 6 mutations:a nonsense mutation(E1099X) in exon26 at nucleotide 3295(3295G>T);a nonsense mutation (R1541X) in exon37 at nucleotide 4621 (4621C>T);a missense mutation in exon40 at nucleotide 5015(5015G>C) changed a highly conserved cysteine to serine (C1672S)in cbEGF24 of FBN1;a base substitution in intron50+1(IVS50+1G>A),was possiblely a mutation of splice site;a missense mutation in exon58 at nucleotide 7241(7241G>A) changed arginine to glutamine (R2414Q) in cbEGF37 of FBN1;a missense mutation in exon 62 at nucleotide 7769(7769G>A) changed a highly conserved cysteine to tyrosine (C2590Y) in cbEGF41 of FBN1. The mutations included 3 missense (3/6),2 nonsense (2/6), 1 splice site (1/6).Four of them were novel.2.We detected 4 single nucleotide polymorphisms (SNP) of FBN1 in the 8 patients by using the same method:IVS27+3A>G,3442C>G(P1148A),IVS45+29insT, IVS62+8A >C.Furthermore,IVS27+3A>G and IVS45+29insT were novel.3.No mutation was detected in TGFBR1 and TGFBR2 genes in the 8 patients by using the same method.Conclusion1.The mutations including missense,nonsense and splice site of FBN1 may caused the corresponding patient to have MFS.2.Four SNPs of FBN1 were not the pathogeny of MFS patients.3.DHPLC is a high efficiency,simple,low-cost and reliable mutation detection method and suits for mutation detection especially in large genes.4.Mutation analysis of the FBN1,TGFBR2 and TGFBR1 genes offers the possibility for a prenatal or presymptomatic diagnosis,particularly in sporadic cases of the disease and in MFS families displaying phenotypic variability.It is also helpful to diagnose and treat for MFS at an early stage.