Clinical relevance of genotype-phenotype correlations beyond vascular events in a cohort study of 1500 Marfan syndrome patients with FBN1 pathogenic variants.

PURPOSE: Marfan syndrome (MFS) is a connective tissue disorder in which several systems are affected with great phenotypic variability. Although known to be associated with pathogenic variants in the FBN1 gene, few genotype-phenotype correlations have been found in proband studies only. METHODS: In 1,575 consecutive MFS probands and relatives from the most comprehensive database worldwide, we established survival curves and sought genotype-phenotype correlations. RESULTS: A risk chart could be established with clinical and genetic data. Premature termination codon variants were not only associated with a shorter life expectancy and a high lifelong risk of aortic event, but also with the highest risk of severe scoliosis and a lower risk for ectopia lentis (EL) surgery. In-frame variants could be subdivided according to their impact on the cysteine content of fibrillin-1 with a global higher severity for cysteine loss variants and the highest frequency of EL surgery for cysteine addition variants. CONCLUSION: This study shows that FBN1 genotype-phenotype correlations exist for both aortic and extra-aortic features. It can be used for optimal risk stratification of patients with a great importance for genetic counseling and personalized medicine. This also provides additional data for the overall understanding of the role of fibrillin-1 in various organs.

Skeletal evolution in Marfan syndrome: growth curves from a French national cohort.

BackgroundTo describe the growth patterns of children affected by Marfan syndrome (MFS) compared with those of unaffected children and to create growth charts.MethodsAn observational study of children referred to the French National MFS Reference Centre. A total of 259 children carrying an FBN1 gene mutation and fulfilling Ghent 1 criteria (MFS group) and 474 mutation-negative sibling controls (non-MFS group) were evaluated. Both groups were compared with French-accepted reference nomograms (Reference group).ResultsBoys and girls from the MFS group were significantly taller than those in the non-MFS group and in the reference group at all ages (P<0.0001). But, MFS children's overgrowth reduced with age. At 17 years of age, the mean height (MFS vs. non-MFS) was 191.2±8.4 cm (+2.9 SD) vs. 182.9±8.1 (+1.6 SD) for boys and 178.3±7.6 cm (+2.7 SD) vs. 169.5±6.8 (+1.2 SD) for girls, respectively. By contrast, the mean BMI of children in the MFS group was similar to those in the non-MFS group and inferior to the values of French general population, evolving around -1 SD.ConclusionGrowth patterns differ in patients with an FBN1 mutation. Knowing the growth parameters should allow physicians to better counsel patients and detect the associated diseases. The provided curves could also help to predict the final height.