An individual homozygous or compound heterozygous for a RYR1 variant(s) classified as pathogenic or likely pathogenic by the ClinGen Malignant Hyperthermia Susceptibility Variant Curation Expert Panel. Individuals who have biallelic (homozygous or compound heterozygous) pathogenic variants in RYR1 generally will have autosomal recessive myopathies and should be managed according to the standard of care for those disorders.