ARFGEF2-Related Periventricular Nodular Heterotopia: A Case Report and Literature Review.

Periventricular nodular heterotopia (PVNH) is a genetically heterogeneous malformation of cortical development with variable neurological outcomes. Among recessive forms, ARFGEF2-related disorder is uniquely characterised by the association of diffuse PVNH and progressive microcephaly. We describe a two-year-old boy born to consanguineous parents who presented with severe developmental delay, hypotonia, progressive microcephaly, and infantile-onset epileptic spasms with developmental regression. Brain MRI showed extensive bilateral PVNH associated with callosal hypoplasia and ventriculomegaly. EEG revealed dysmature background activity with multifocal epileptiform discharges and runs of asynchronous fast activity during sleep. Genetic testing identified a novel homozygous nonsense variant in ARFGEF2. The clinical course was characterised by drug-resistant epilepsy and multisystemic involvement, including feeding difficulties and recurrent respiratory infections. To contextualise this case, we performed a comprehensive review of previously reported patients, further delineating the clinical, neuroradiological, and electroclinical spectrum of ARFGEF2-related disorder. This case highlights progressive microcephaly as a key distinguishing feature of ARFGEF2-related PVNH and underscores the importance of early genetic diagnosis to guide targeted surveillance for extra-CNS complications and multidisciplinary care.