Central Core Myopathy with Mutation of the RYR1 Gene in Combination with Mutation of the COL6A2 Gene and Severe Infantile Myoclonic Epilepsy

Abstract

Children with central core myopathy (CCD) are diagnosed by the clinical symptom of muscle hypotonia. Primarily, the diagnosis is made by muscle biopsy. The disease is caused by mutation in the RYR1 gene. Dysfunction of the ryanodine receptor results in dysregulation of calcium metabolism in the sarcoplasmic reticulum of muscle cells. Our patient showed typical symptoms of congenital myopathy and dislocation of the hip from birth. The diagnosis of CCD was made by muscle biopsy and confirmed by a gene test which showed mutation in the RYR1 gene. In addition, there was a mutation in the COL6A2 gene, which may encode for congenital muscular dystrophy type Ulrich. At the age of approximately 8 months, the child developed the symptoms of severe infantile myoclonic epilepsy with generalized irregular polyspikes in the electroencephalography (EEG). Seizures could be reduced by treatment with various antiepileptic drugs. However, by introducing valproate and zonisamide, the EEG almost normalized and the convulsions stopped. In literature, there are no data about the combination of the mutation in the RYR1 gene and severe epilepsy. As the CCD is a dysfunction of the intracellular calcium channels, it must be assumed that the epilepsy is probably caused by central nervous system involvement of the channel dysfunction. This essential aspect has to be taken into consideration when deciding on the appropriate antiepileptic drug choice.