Qualitative or quantitative defects of protein SERCA1

Qualitative or quantitative defects of protein SERCA1 (also known as defects of the sarco/endoplasmic reticulum calcium ATPase 1, encoded by the ATP2A1 gene) are associated with Brody disease (Brody myopathy). SERCA1 is a calcium pump critical for the reuptake of calcium ions into the sarcoplasmic reticulum of skeletal muscle after muscle contraction. When this protein is deficient or dysfunctional, calcium clearance from the cytoplasm is impaired, leading to delayed muscle relaxation. The condition primarily affects the skeletal muscular system. Patients with Brody disease typically experience exercise-induced muscle stiffness, cramping, and impaired muscle relaxation (pseudomyotonia), particularly affecting the legs, arms, and eyelids. Symptoms are often worsened by cold temperatures and vigorous physical activity. Unlike true myotonia, electromyography (EMG) typically shows electrically silent muscle contractures. Onset is usually in childhood, though symptoms may become more apparent with age and increased physical demands. There is currently no specific curative treatment for Brody disease caused by SERCA1 defects. Management is primarily supportive and symptomatic, including avoidance of triggers such as cold exposure and overexertion. Some patients may benefit from calcium channel blockers such as verapamil or dantrolene sodium to help manage muscle stiffness, though evidence is limited. Physical therapy and lifestyle modifications are also recommended. The condition is considered rare, and genetic counseling is advised for affected families.

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