 However, Beals and Hecht discovered in 1972 that, unlike Marfan's, CCA is caused by mutations to the fibrillin-2 ("FBN2") gene rather than the fibrillin-1 ("FBN1") gene.CCA is characterized by contractures of varying degrees, mainly involving the large joints, which are present in all affected children at birth.The contractures may be mild and tend to improve over time, but permanently bent fingers and toes (camptodactyly) are almost always present.