Clinical variations of epileptic syndrome associated with PACS2 variant

Background Recent studies have suggested that two PACS2 pathogenic variants, c.625G > A (p.Glu209Lys) and c.631G > A (p.Glu211Lys), have been causally linked to the characteristic developmental and epileptic encephalopathy, including autistic behaviors, hypotonia, cerebellar dysgenesis and facial dysmorphism. Their seizures appear most difficult to control in neonatal and infant period, but improve after the first year of life. We herein report three patients with the same PACS2 variant, c.625G > A (p.Glu209Lys), showing different characteristics from previous reports. Case report Case 1, a 2-year-old girl, developed frequent tonic convulsions 2 weeks after birth. Brain magnetic resonance imaging showed a decrease in posterior periventricular white matter volume, an enlargement of the inferior horn of lateral ventricles and old subependymal hemorrhage. Epilepsy is now controlled with antiepileptic drugs. Case 2, a 12-year-old girl, developed generalized tonic convulsions 3 days after birth. Although epilepsy had been controlled since the age of 4, she developed Lennox–Gastaut syndrome at 9 years old. Case 3, a 3-year-old girl, developed tonic convulsions 3 days after birth. She now exhibits normal psychomotor development, and epilepsy is controlled without medicine. Conclusion PACS2-related epileptic syndrome presents variable phenotypes than previously reported. We think that our findings expand the clinical spectrum of this disease, and provide important information about the differential diagnosis of neonatal-onset epileptic syndrome.