What causes MYH7-related scapuloperoneal myopathy ?
What causes MYH7-related scapuloperoneal myopathy? MYH7-related scapuloperoneal myopathy is caused by mutations in the MYH7 gene. This gene, located on chromosome 14q12, provides instructions for making a protein known as the cardiac beta ()-myosin heavy chain. This protein is found in heart (cardiac) muscle and in type I skeletal muscle fibers. Type I fibers, which are also known as slow-twitch fibers, are one of two types of fibers that make up skeletal muscles. Type I fibers are the primary component of skeletal muscles that are resistant to fatigue. For example, muscles involved in posture, such as the neck muscles that hold the head steady, are made predominantly of type I fibers.