Pyridoxine Responsive Seizures: Beyond Aldehyde Dehydrogenase 7A1

Objective Pyridoxine responsive seizures (PDRs) are characterized by early-onset seizures and epileptic encephalopathy (neonates and infants) which respond to pyridoxine. Any type of seizures can be the first presentation of PDRs in these children. The aim of this 20-year retrospective study was to report the profile of 35 children with PDRs. Materials and Methods Neonatal and infantile seizures responding to pyridoxine were analyzed retrospectively from 1998 to 2018. Depending on the clinical features, laboratory results, and genetic study, they were divided into following four groups: (A) responders with α-aminoadipic semialdehyde dehydrogenase 7A1 ( ALDH7A1 ) mutation, (B) responders with pyridoxal phosphate homeostasis protein (PLPHP) mutation, (C) responders with none of these two known mutations, (D) and responders in combination with antiepileptic medications. Results Sixteen of 35 children had genetic mutation, 4 with ALDH7A1 mutation, and 12 with PLPHP mutation recently described. Nineteen of 35 children had no genetic positivity. Conclusion A large number of children with pyridoxine response do not have known genetic confirmation. Over time, new genes, responsible for pyridoxine dependency, may be identified or an unknown metabolic disorder may be seen in these children.