Epilepsy Spectrum Associated with PRRT2 Variants: Case Presentations

Abstract

Variations in the PRRT2 gene have been shown to cause a variety of diseases, including benign familial infantile epilepsy (BFIE) and paroxysmal kinesigenic dyskinesia (PKD). Next-generation sequencing techniques have allowed the broadening of this disease spectrum. In this study, we aimed to present patients with epilepsy who were shown to have PRRT2 variants in our clinic. The characteristics of 13 patients with epilepsy, including two families with PRRT2 variants and one patient with a sporadic homozygous variant, were reviewed by screening the epilepsy archive. P.R217Pfs∗8 variation was detected in patients of our first family with both BFIE and PKD diseases. This family was included in the article in which this gene was first described in 2012. In the first generation there were 3 patients with BFIE, in the second generation there were 2 patients with BFIE-PKD and one patient with BFIE. The second family had only BFIE. In this family, the c.604_607del (p.Ser202HisfsTer26) variation was detected in the PRRT2 gene in the index case. In this phenotypically homogeneous family, BFIE was present in all 3 generations. Although the seizures remitted, electroencephalography abnormalities continued for 2 years in our index case. Migration of the epileptogenic focus to the posterior of the hemispheres over time is an interesting observation. Our sporadic case was a patient with a diagnosis of juvenile absence epilepsy, and a homozygous c.67G>A;p.(Glu23Lys) variant was detected in this patient. Findings in PRRT2-associated epilepsy patients show the importance of next-generation sequencing techniques. It indicates that different epilepsy phenotypes can be seen in variations associated with a single gene. With better recognition of epilepsy associated with PRRT2 gene variants, which are considered as synaptopathy, it will be possible to switch from current symptomatic treatments to therapeutic options targeting specific pathophysiological changes.

Keywords

• synaptopathy
• benign familial infantile epilepsy
• paroxysmal kinesigenic dyskinesia
• prrt2