Also known as nemaline myopathy and nemaline rod myopathy, rod myopathy pertains to a congenital, hereditary neuromuscular disease characterized by progressive and non-progressive muscle weakness of varying severity. Rod myopathy is clinically classified into several groups, ranging from mild (typical), intermediate, severe, to adult-onset. However, this categorization is somewhat ambiguous, with categories commonly overlapping.

Rod myopathy has a wide range of physical presentations, but the most common symptom is weakness concentrated in the proximal muscles. The most frequently affected areas are the bulbar, respiratory, and trunk muscles. Individuals with severe rod myopathy usually show symptoms at birth; while those with mild or intermediate rod myopathy may initially appear unaffected. Children born with the disease frequently gain strength as they grow; however, muscle weakness takes a heavy toll on body features through time. Meanwhile, adults with rod myopathy tend to have a very slender physique. In general, patients with severe rod myopathy have restricted limb movement. Some use wheelchairs for mobility during their lifetime. Scoliosis and osteoporosis also appear to be common problems because of the weakness of the trunk muscles. As in many neuromuscular disorders, respiratory complications may also arise. Babies born with the disease suffer from respiratory distress soon after birth. Most require a tracheostomy for breathing assistance. In addition, throat (bulbar) muscle impairment is a main symptom of rod myopathy. Most affected patients have difficulty swallowing and require feeding tubes for daily nutrition. Communication skills and speech may also be impaired due to the poor closure of the velopharyngeal port, an area between the soft palate and the back of the throat.

rodmyopathy