RYR1 and myopathy: Furthermore, a number of other myopathies associated with RyR1 missense variants, such as Central Core Disease (CCD) and Multiminicore disease (MmD), manifest as muscle weakness, which can range from mild to life threatening (Robinson et al., 2006), and knock-in mice carrying one of the most common CCD RyR1 variants (I4895T) demonstrated reduced muscle strength (Loy et al., 2011).