SGCD and Menkes disease: Thbs4-/- mice alone at three months of age showed minimal or no pathological changes in skeletal muscle, although combinatorial Thbs4-/- Sgcd-/- or Thbs4-/- mdx mice showed a significant worsening of MD, including greater histopathology, greater serum CK levels and reduced treadmill running performance, compared with single null Sgcd and mdx mice (Figure 3A–C; Figure 3—figure supplement 1A–C).