Pathogenic variants in genes encoding collagens cause connective tissue disorders, including osteogenesis imperfecta, Ehlers–Danlos syndrome, and Gould syndrome (caused by mutations in COL4A1 and COL4A2), and pathogenic variants in genes encoding proteins required for collagen biosynthesis can cause similar but overlapping clinical phenotypes. This evidence concerns the gene COL4A2 and connective tissue disorder.