Myoclonic seizures of inherited glycosylphosphatidylinositol deficiency treated with diazepam and clonazepam: a case report

Inherited glycosylphosphatidylinositol deficiencies (IGDs) are characterized by intractable epilepsy and developmental delay. Here, we report a three-year-old girl with an overlapping phenotype involving a compound heterozygous mutation (c.224T>C [p.I75T]; c.3139A>G [p.K1047E]) in the phosphatidylinositol glycan anchor biosynthesis class O (PIGO) gene. Our findings support the diagnosis of PIGO as a monogenic disease gene for developmental and epileptic encephalopathy. IGD-related epilepsy is usually intractable; however, seizures were completely controlled using diazepam and clonazepam with pyridoxine in our patient with mild developmental delay. Treatment with pyridoxine and benzodiazepine might be effective for the treatment of myoclonic seizure due to IGDs.