Mutations in the CAPN3 gene cause muscular dystrophies with dysfunction in calpain-3. Calpainopathies are usually inherited in an autosomal recessive manner but in some families they can occur in a dominant inheritance. The significance of heterozygous variants is difficult to interpret in the absence of family history. In this study, the investigators will review the clinical and laboratory information in a cohort of patients identified in the participating centers, with the aim of improving the diagnostic strategy of dominant calpainopathies.

The investigators will review clinical and biomarker information in a cohort of 50 patients with heterozygous variants in the CAPN3 gene. Patients are referred by participating centers who will provide anonymised information on the clinical phenotype and laboratory test results. Suitable subjects will be contacted to obtain informed consent. Pseudonymised anamnestic data will be collected from the patient's clinical history and medical records.The aim is to identify a set of multidisciplinary data sufficient to define a diagnostic algorithm for the dominant calpainopathies.

Inclusion Criteria:

• Clinical LGMD phenotype, family history with dominant inheritance or sporadic cases, single variant in CAPN3, second variant excluded by MLPA (Multiplex Ligation Probe Amplification) or by analysis of mRNA extracted from muscle.

Exclusion Criteria:

• No variants in CAPN3, two variants in CAPN3

Suitable subjects identified in the participating centers.

Data and images may be disclosed in strictly anonymous form through meetings, conferences and scientific publications. In any case, the name or any other detail suitable for identifying the individual participant will not be disclosed as the data may only be presented in aggregate form.