[Aicardi-Goutières syndrome with atypical presentation: RNASEH2B gene mutation in an infant without microcephaly or intracranial calcifications (a case report)].

Aicardi-Goutières syndrome (AGS) is a rare genetic encephalopathy frequently misdiagnosed as other pediatric neurological conditions. We report the case of a 14-month-old infant who developed psychomotor regression from the age of 6 months, exhibiting an atypical presentation characterized by the absence of microcephaly and intracranial calcifications. Cerebral MRI revealed only mild cortico-subcortical atrophy. Following systematic exclusion of infectious and metabolic etiologies, genetic analysis identified a homozygous mutation in the RNASEH2B gene, confirming the diagnosis of AGS. This case highlights the phenotypic heterogeneity of the syndrome and the crucial importance of genetic sequencing in diagnosing early-onset encephalopathies of undetermined origin, even in the absence of classic clinical and radiological markers.