Background: The inositol polyphosphate 4-phosphatase intracellular signaling pathway is susceptible to genetic or epigenetic alterations that may result in major neurological illnesses with clinically significant pons and cerebellum involvement. Case reports: A seven-year-old girl with pontocerebellar hypoplasia, resistant myoclonic epilepsy with axial hypotonia, microresponse, contractures in wrists and ankles and growth retardation, whole-exome sequencing was performed and a homozygous "NM_001134225.2:c.646C > T, p.(Arg216Ter)" variant was found in the INPP4A gene. Conclusion: INPP4A mutations should be kept in mind in cases with severely delayed psychomotor development, progressive microcephaly, resistant myoclonic epilepsy, isolated cerebellum, and pons involvement. (c) 2023 Published by Elsevier B.V. on behalf of The Japanese Society of Child Neurology. All rights reserved.