FBN1 and congenital contractural arachnodactyly: Mutations in the fibrillin genes cause alterations in elastogenesis and connective tissue disorder conditions, such as Marfan syndrome or Weill-Marchesani syndrome if mutations occur in the FBN1 gene, or congenital contractural arachnodactyly (Beals syndrome) if the FBN2 gene is altered.