COL6A1 and Ullrich congenital muscular dystrophy: We finally investigated whether the resistant cells also had a lower incidence of mitochondrial ultrastructural abnormalities, which are characteristic of the mouse Col6a1−/− model (Irwin et al., 2003) and can also be observed in cultures established from muscle biopsies of UCMD and BM patients (Angelin et al., 2007).