Slow-twitch fibers from soleus muscle biopsies of carriers and patients suffering myosin-based, inherited cardiomyopathies are an established ex vivo model for studying the disease mechanism in humans (Kohler et al., 2002; Kirschner et al., 2005; Seebohm et al., 2009). The gene discussed is MYH14; the disease is cardiomyopathy.