COL12A1 and Bethlem myopathy 2: (63) Despite a complete knockdown of this gene causing bone fragility in mice,(64) pathogenic variants in COL12A1 are associated with recessive Ullrich congenital muscular dystrophy 2 (MIM 616470), dominant Bethlem myopathy 2 (MIM 616471), or myopathic EDS,(65) but not fractures.