FBN1 and Marfan syndrome: While the majority of pathogenic variants in FBN1 result in the phenotypes of MFS, there are also paradoxical phenotypes that have opposite signs and symptoms, including short stature and thick tight skin (Table 1), leading to the classification of FBN1 variants as “tall” and “short” (Charbonneau et al. 2004; Peeters et al. 2022), reflecting the differences in skeletal phenotype.