Nemaline myopathy 2 is an inherited skeletal muscle disorder that causes severe muscle weakness, hypotonia, and reduced or absent reflexes.
Individuals with nemaline myopathy have muscle weakness (myopathy) throughout the body, but most severely in the muscles of the face, neck, trunk, and other muscles close to the center of the body. This muscle weakness tends to worsen over time. Other symptoms include feeding and swallowing difficulties, foot deformities, abnormal curvature of the spine (scoliosis) and joint deformities (contractures). Signs and symptoms are typically present at birth or early childhood. The level of severity in symptoms varies greatly with nemaline myopathy, with most affected individuals retaining the ability to walk, however more serious cases require the use of a wheelchair, and at the most serious, the muscles used for breathing can be affected causing life-threatening breathing difficulties. There is no known cure or successful treatment for this condition.
With nemaline myopathy 2, the condition is caused by pathogenic (disease-causing) variants in the NEB gene. These variants to the NEB gene exhibit autosomal recessive inheritance, which means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 108 chance to be a carrier. Carriers of this condition do not typically display any signs or symptoms.
Other names for this condition include NEB-related nemaline myopathy, rod body disease, and rod myopathy.