Antoniel et al. [98] examined biopsies of the pedidium tendon from a UCMD patient with a heterozygous COL6A1 mutation and of the piriformis tendon from a BM patient with heterozygous COL6A2 mutation who had a femur fracture surgeryand compared them with two biopsies of similar tendons from controls who had surgery for other reasons. The gene discussed is COL6A2; the disease is Ullrich congenital muscular dystrophy.