Detection of thirty novel FBN1 mutations in patients with Marfan syndrome or a related fibrillinopathy

Abstract

Marfan syndrome (MFS) is a disorder of the extracellular matrix caused by mutations in the gene encoding fibrillin-1 (FBN1). Recent studies have illustrated the variability in disease severity and clinical manifestations of MFS. Useful genotype-phenotype correlations have been slow to emerge. We screened 57 unrelated patients with MFS or a Marfan-like phenotype using a combination of SSCP and/or DHPLC. We detected 49 different FBN1 mutations, 30 (62%) of which were novel. The mutations comprised 38 substitutions (78%), 10 deletions (20%), and one duplication (2%). There were 28 missense (57%), nine frameshift (18%), eight splice site (16%), and four nonsense mutations (8 %). Genotype-phenotype analysis revealed that patients with an identified FBN1 mutation were more likely to have ectopia lentis and cardiovascular complications compared to those without an identifiable mutation (relative risks of 4.6 and 1.9, respectively). Ectopia lentis was also found to be more prevalent in patients whose mutations involved a cysteine substitution (relative risk 1.6) and less prevalent in those with premature termination mutations (relative risk 0.4). In our hands, we achieved 93% mutation detection for DHPLC analysis of patients who fulfilled the Ghent criteria. Further analysis of detailed clinical information and mutation data may help to anticipate the clinical consequences of specific FBN1 mutations.