However, these histopathologic features are not unique to RYR1-RM, can be dynamic over time, may vary based on biopsy site, and may be absent when biopsy is performed at an early age [25, 26] or reflect a consequence of the gene dose (heterozygous = MH susceptibility versus homozygous = clinical myopathy) [27]. Here, RYR1 is linked to myopathy.