Mondo Description Tubular aggregate myopathy is a disorder that affects the skeletal muscles. Signs and symptoms typically begin in childhood and worsen over time. The leg muscles are most often affected, but the arm muscles may also be involved. Symptoms include muscle pain, cramping, weakness or stiffness; and exercise-induced muscle fatigue. Affected individuals may have an unusual walking style (gait) or difficulty running, climbing stairs, or getting up from a squatting position. Some individuals develop contractures. This condition may be caused by mutations in the STIM1 or ORAI1 genes. It is usually inherited in an autosomal dominant manner, but autosomal recessive inheritance has also been reported.