Open Access

Jan Henje Döring, Afshin Saffari, Thomas Bast, Knut Brockmann, Laura Ehrhardt, Walid Fazeli, Wibke Gesine Janzarik, Gerhard Kluger, Hiltrud Muhle, Rikke S. Møller, Konrad Platzer, Joana Larupa Santos, Iben Bache, Astrid Bertsche, Michaela Bonfert, Ingo Borggräfe, Philip Julian Broser, Alexandre N. Datta, Trine Bjørg Hammer, Hans Hartmann, Anette Hasse-Wittmer, Marco Henneke, Hermann Kühne, Johannes Rudolph Lemke, Oliver Maier, Eva Matzker, Andreas Merkenschlager, Joachim Opp, Steffi Patzer, Kevin Rostasy, Birgit Stark, Adam Strzelczyk, Celina Steinbeis-von Stülpnagel, Yvonne G. Weber, Markus Wolff, Birgit Zirn, Georg Friedrich Hoffmann, Stefan Kölker, Steffen Syrbe

• Pathogenic variants in PRRT2, encoding the proline-rich transmembrane protein 2, have been associated with an evolving spectrum of paroxysmal neurologic disorders. Based on a cohort of children with PRRT2-related infantile epilepsy, this study aimed at delineating the broad clinical spectrum of PRRT2-associated phenotypes in these children and their relatives. Only a few recent larger cohort studies are on record and findings from single reports were not confirmed so far. We collected detailed genetic and phenotypic data of 40 previously unreported patients from 36 families. All patients had benign infantile epilepsy and harbored pathogenic variants in PRRT2 (core cohort). Clinical data of 62 family members were included, comprising a cohort of 102 individuals (extended cohort) with PRRT2-associated neurological disease. Additional phenotypes in the cohort of patients with benign sporadic and familial infantile epilepsy consist of movement disorders with paroxysmal kinesigenic dyskinesia in six patients, infantile-onset movement disorders in 2 of 40 individuals, and episodic ataxia after mild head trauma in one girl with bi-allelic variants in PRRT2. The same girl displayed a focal cortical dysplasia upon brain imaging. Familial hemiplegic migraine and migraine with aura were reported in nine families. A single individual developed epilepsy with continuous spikes and waves during sleep. In addition to known variants, we report the novel variant c.843G>T, p.(Trp281Cys) that co-segregated with benign infantile epilepsy and migraine in one family. Our study highlights the variability of clinical presentations of patients harboring pathogenic PRRT2 variants and expands the associated phenotypic spectrum.