Overview: Changes in the RYR-1 gene are the most common cause of congenital myopathies. The RYR-1 receptor in muscle cells regulates the flow of calcium. A reduced number and/or abnormal RYR-1 receptors lead to dysfunctional muscle contraction. Symptoms are variable among individuals with RYR-1-related diseases, but are typically not progressive or very slowly progressive.
Symptoms: Common symptoms include ophthalmoparesis and muscle weakness, typically affecting the proximal muscle. Some individuals experience muscle cramping and pain, difficulties exercising, and intolerance to heat. There are variable breathing problems associated with RYR-1-related diseases ranging from mild (requiring no breathing support to CPAP/BiPAP during sleep) to severe (requiring continuous mechanical ventilator). There are typically no heart problems and intelligence is not affected.
Malignant Hyperthermia: Changes in the RYR-1 gene have also been associated with malignant hyperthermia, a severe and potentially fatal reaction to certain types of anesthesia . Anyone with an RYR-1 genetic abnormality should take "malignant hyperthermia precautions" if anesthesia is required for a medical/surgical procedure.
Diagnosis: RYR-1-related diseases can be diagnosed through muscle biopsy, muscle MRI, and genetic testing. Muscle biopsy looks for changes in the muscle that may be associated with the RYR-1 gene at the cellular level. Muscle MRI allows the doctors to look at the muscles of the leg that are affected at the structural level. There is a specific pattern of muscles affected associated with changes in the RYR-1 gene. Lastly, the diagnosis is confirmed by genetic testing. A change in the RYR-1 gene can be spontaneous or inherited in the family. There are 2 types of inheritance patterns for changes in this gene, autosomal dominant and autosomal recessive.
Treatment: At this time, no cure exists for RYR-1-related diseases. However, many research studies are being conducted to find new treatments and hopefully a cure. The goal of this Foundation is to help find one.
To get a more in-depth overview written by Dr. Michael Goldberg, MD, MPH for NORD, please click HERE.