ABSTRACT
[ ABSTRACT] AIM:To investigate the genetic cause of 2 Chinese families with Marfan syndrome .METHODS:The clinical and laboratory investigations were performed in the 2 unrelated Chinese families .Family 1 had 1 patient with cardiac problem.Family 2 had 2 patients:one died, and the other with respiratory and cardiac problems .Next generation sequencing and Sanger sequencing in the Marfan syndrome causal gene FBN1 were performed in the patient , his unaffected sister and the parents of family 1.Sanger sequencing covering all the exons and intron-exon boundaries were performed in the patient and the parents in family 2.Bioinformatic analysis was engaged in the variations unravelled .Fifty healthy indi-viduals were also investigated in the same manner .RESULTS:Both patients were diagnosed with Marfan syndrome .A no-vel mutation c.4685G>A (p.Cys1562Tyr) was detected in the patient of family 1 but was absent in his parents and the unaffected sister .This is a previously unreported novel mutation .In the mutation a conserved Cys was substituted by a Tyr in amino acid 1562 affecting a TGF-βbinding domain and the secondary structure in the encoded protein .We also detected the mutation c.3706T>C (p.Cys1236Arg) in the patient of family 2.It was absent in the unaffected parents , and there-fore was a de novo mutation too.This mutation has been previously reported and known to be associated with neonatal Marfan syndrome .Both mutations were absent in the 50 healthy controls .We also compared the genotype and phenotypes of the 2 families.CONCLUSION:We report 2 de novo mutations in 2 Chinese families with Marfan syndrome .One of the 2 mutations is novel.The phenotype of the mutation c.4685G>A(p.Cys1562Tyr) in family 1 is associated with classical Marfan syndrome, while that of c.3706T>C (p.Cys1236Arg) in family 2 is with neonatal type of Marfan syndrome .De novo mutations may be a cause for a proportion of mutations underlying the disease .The novel mutation also expends the mutational spectrum of the FBN1 gene.