Genetic cause of epilepsy in a Greek cohort of children and young adults with heterogeneous epilepsy syndromes.

We describe a cohort of 10 unrelated Greek patients (4 females, 6 males; median age 6.5 years, range 2-18 years) with heterogeneous epilepsy syndromes with a genetic basis. In these patients, causative genetic variants, including two novel ones, were identified in 9 known epilepsy-related genes through whole exome sequencing. A patient with glycine encephalopathy was a compound heterozygote for the p.Arg222Cys and the p.Ser77Leu variant. A patient affected with Lafora disease carried the homozygous p.Arg171His variant. A heterozygous variant in the gene (p.Pro282Thr) was found in one patient and a pathogenic variant in the gene (p.Gly820Val) in another patient. Infantile-onset lactic acidosis with seizures was associated with the p.Arg446Ter gene variant in one patient. In two additional epilepsy patients, the p.Ala1662Val and the novel non-sense p.Phe1330Ter gene variants were found. Finally, in 3 patients we observed a novel heterozygous missense variant in (p.Ala1874Thr), a heterozygous splice site variant in (c.517-2A>G), as a cause of Glut1 deficiency syndrome, and a pathogenic variant in (p.Arg292Leu), respectively. In half of our cases (patients with variants in the , , and genes), a genetic cause with potential management implications was identified.