Teaching NeuroImages: Neuroimaging Findings in Inosine Triphosphate Pyrophosphohydrolase Deficiency.

Abstract

A 9-month-old girl presented with global developmental delay and refractory generalized seizures. Microcephaly, poor visual fixation, and intermittent dystonic posturing were observed on clinical examination. MRI brain (figure) revealed delayed myelination and restricted diffusion involving optic radiations, cerebral peduncles, red nuclei, globus pallidi, and corticospinal tract. EEG showed background slowing and multifocal epileptiform discharges. Workup revealed a homozygous, likely pathogenic variant in ITPA (c.124+1 G>A) and reduced inosine triphosphate pyrophosphohydrolase (ITPase) activity in skin fibroblasts (0.19 nmol/mg protein × h, controls 6.86 ± 2.51). Imaging pattern of delayed myelination and restricted diffusion is suggestive of ITPase deficiency in a child presenting with early infantile epileptic encephalopathy.1,2