Calpainopathy is an autosomal recessive limb girdle muscular dystrophy (LGMD2A) caused by mutations in CAPN3 gene. Objective To present clinical and histological findings in six children with a molecular diagnosis of LGMD2A and additionally the MRI findings in two of them. Method We retrospectively assessed medical records of 6 patients with mutation on CAPN3 gene. Results All patients were female (three to 12 years). The mean of age of disease onset was 9 years. All of them showed progressive weakness with predominance in lower limbs. Other findings were scapular winging, joint contractures and calf hypertrophy. One female had a more severe phenotype than her dizygotic twin sister that was confirmed by muscle MRI. Muscle biopsies showed a dystrophic pattern in all patients. Conclusion In this cohort of children with LGMD2A, the clinical aspects were similar to adults with the same disorder.

AGRADECIMENTOSÀ minha família, minha mãe, meu irmão, minhas irmãs, meus sobrinhos e em especial ao meu pai que não se encontra mais presente fisicamente, mas sei que está sempre me acompanhando em espírito.À Dante Souza e Souza, por ser meu porto seguro em todas as situações.Ao Prof. Dr. Edmar Zanoteli pela orientação e pela oportunidade oferecida e ao Prof. Dr. Gerson Chadi por todo o apoio durante a realização da pesquisa; LGMD2A, six (17%) with LGMD2I, and on 21 of them (58%), it was not possible to identify the specific subtype. Pathogenic mutations on CAPN3 were found in eight patients, being homozygous in two cases, compound heterozygous in five cases and heterozygous in one case. The diagnosis of LGMD2A in one patient was done based exclusively by CAPN3 protein analysis on the muscle tissue.Pathogenic mutations on FKRP were found in six patients, being homozygous in five cases and heterozygous in one case. Most of the patients with LGMD2I (five cases) presented the mutation c.826C>A. It was observed total or partial absence of the CAPN3 expression in patients with LGMD2A. Conclusions: The study showed that mutations on CAPN3 and FKRP are frequent in patients with clinical and histological diagnosis of LGMD. The CAPN3 expression analysis proved as an important tool in the LGMD2A diagnosis.