COL6A3 and hyperinsulinemic hypoglycemia, familial, 4: Although a modest reduction in Col6a3 mRNA (Fig. 3c) and collagen VI protein (Fig. 3g) was observed in ETPKO-sham kidneys, this did not coincide with in any signs of muscle dysfunction, the major phenotype associated with actual collagen VI deficiency, as evidenced by normal skeletal muscle weights (Supplementary Fig. 4a), histology (Supplementary Fig. 4b) and grip strength performance (Supplementary Fig. 5) in ETPKO mice.