In the CM group, we identified the COL12A1 variant c.5894G>A and the COL6A1 variant c.850G>A, which have been previously reported in patients with Bethlem myopathy or Ullrich congenital muscular dystrophy (Lampe and Bushby, 2005; Butterfield et al., 2013; Naghipoor et al., 2023). Here, COL12A1 is linked to Bethlem myopathy.