Study design: The Spanish registry of RYR1 and CACNA1S polymorphisms (RYCA) is an anonymous descriptive observational multicentre study that aims to identify and catalogue the variants or polymorphisms in the RYR1 and CACNA1S genes in the Spanish population. Secondarily, its correlation with the binding mutations described in both genes at European level by the EMHG will be evaluated to assess the incidence of malignant hyperthermia in Spain. The RYCA registry complies with the highest standards of European and international homologation, both with regard to computer security and the protection of personal data (Data Protection Law 15/1999).

Hypothesis: Performing a Spanish registry of RYR1 and CACNA1S polymorphisms will contribute to describe the variants present in our environment and determine their relationship with MH susceptibility.

Objectives:

• Describe the national polymorphisms of the RYR1 and CACNA1S genes
• To evaluate the incidence of genetic MH susceptibility according to the recommendations of the EMHG.

The presence of polymorphisms in a population that has not been studied before may have a difficult correlation with the mutations described in the EMHG webpage.

Eligibility Criteria: The sample contained in the registry will originate from the genetic data of patients unrelated to HM who have been sequenced the RYR1 and CACNA1S gene by another pathology. The data related to the genetic analysis will be provided without identifying data of the patient or the clinical history. There will be no possibility of identification of the patient by the team responsible for the RYCA registry, so the request for informed consent is not viable. There will be no selection of participants or patient follow-up.

Methodology: A preliminary pilot study will be conducted in an unselected anonymous cohort of the sequenced exome database of the RYR1 and CACNA1S gene at the La Fe Health Research Institute (IISlaFe). The population contained in this database is random and unrelated to HM and the patients are anonymous, so we do not have access to personal data or medical history. If the analysis is feasible, a request for collaboration will be transferred to the Genetics Services / Research Units with experience in the exome sequencing of the RYR1 and CACNA1S genes. Anonymous readings will be requested to carry out the registration and description of the variants existing in the Spanish population and their relationship with the variants described by the EMHG.

Variables: The registry will include the chromosomal coordinates, number of total patients included, number of patients whose variant is in heterozygosis, number of patients whose variant is in homozygosis and allelic frequency. Thus, for each of the genes of interest, and making use of their respective chromosomal coordinates, information regarding the variants that these might include will be extracted.

Sample size. Sample size calculation is not considered since it is a descriptive record.

The sample contained in the registry will originate from the genetic data of patients unrelated to malignant hyperthermia who have been sequenced the RYR1 and CACNA1S gene by another pathology. The data related to the genetic analysis will be provided without identifying data of the patient or the clinical history. There will be no possibility of identification of the patient by the team responsible for the RYCA registry, so the request for informed consent is not viable. There will be no selection of participants or patient follow-up.

Inclusion Criteria: Patents with malignant hyperthermia which genes RYR1 and CACNA1S have been sequenced for another pathology