Individuals with no significant seizure reduction (defined as >= 50 % reduction in seizure frequency after 3 months of treatment) with maximum daily dosage of pyridoxine were offered a switch from oral pyridoxine to oral P5P. Seizure types included bilateral tonic-clonic seizures ( I n i = 4), absence seizures ( I n i = 2), focal seizures with or without impaired awareness ( I n i = 3), focal to bilateral tonic-clonic seizures ( I n i = 2), myoclonic seizures ( I n i = 2), and tonic seizures ( I n i = 1). Although the treatment period was too short to observe any convincing changes in the first two seizure types, a drastic reduction in focal seizures (>90%) was seen during the last 8-10 weeks of pyridoxine treatment. ABBREVIATIONS ASM Antiseizure medication GPI Glycosylphosphatidylinositol P5P Pyridoxal 5-phosphate TNSALP Tissue non-specific alkaline phosphatase Introduction The glycolipid glycosylphosphatidylinositol (GPI) plays an important role in both embryonic development and neurogenesis.1,2 GPI is synthesized in the endoplasmic reticulum, transferred to proteins, and later modified in the Golgi apparatus.3 At least 31 genes are involved in this multistep pathway and, to date, pathogenic variants in 22 of these genes have been associated with human disease.4 The pattern of inheritance is autosomal recessive in all but one gene; I PIGA i is located on the X chromosome and inheritance is X-linked recessive. [Extracted from the article]