The LMNA gene produces lamine A and lamine C protein. Laminopathies are a group of heterogeneous diseases that result from changes in certain membrane proteins surrounding the nucleus of all cells.
LMNA-CMD is predominantly innate and is on the severe end of the spectrum. Affected individuals have weak neck and armpit muscles and may not be able to sit independently.
There are contractures of the spine, hip, knee and Achilles tendons. Scoliosis and spinal stiffness may develop. Some patients manage to walk for a short time, but then lose this ability. Serious respiratory failure develops. Cardiac involvement or abnormalities may occur. The heart can be affected in two different ways: heart rhythm disturbances (arrhythmias) and an enlarged heart (cardiomyopathy). This causes disturbances in the conduction system (electrical impulse that stimulates the contraction of the heart muscle) and the risk of sudden death.
LMNA-CMD is inherited in an autosomal dominant manner. There are two other forms of this disease that progress more slowly, called EDMD2 and EDMD3. EDMD2, autosomal dominant; EDMD3 is inherited autosomal recessively.