Varying phenotypic spectrum in paroxysmal exercise-induced dystonia: a Turkish family with SLC2A1 pathogenic variant

Abstract

Introduction: Paroxysmal exercise–induced dyskinesia (PED) is characterized by repeated episodes of involuntary movement disorders that are typically caused by prolonged walking or running and mostly caused by SLC2A1 gene mutations. Phenotypes vary from focal dystonia, ataxia, tremor, and complex non-kinesigenic movements to other movement disorders in patients with SLC2A1 mutation. Also, SLC2A1 mutations carriers may present with also other phenotypes such as epileptic seizure and migraine. Case reports: We report fve patients with various phenotypic spectrums of PED in a Turkish family. Whole exome sequencing revealed a likely pathogenic synonymous variant p.Ser324Ser (c.972G>A) in the SLC2A1 gene (ENST00000426263.3) and the variant segregated in all afected family members. Also, other than PED, the phenotypical spectrum of afected individuals in this family includes epilepsy, mental retardation, and weakness. Conclusions: We concluded that family members with the same SLC2A1 gene mutation may show very heterogenous phenotypes. Clinicians should be aware of wide variety of symptoms of the patients with PED. We also emphasized that even if a mutation in the coding sequence does not make an amino acid change, it may cause the disease.