Warburg Micro Syndrome Type 3 Presenting with Global Developmental Delay and Dyskinesia

Abstract Warburg micro syndrome (WMS) is an autosomal recessive neurodevelopmental disorder characterized by congenital ocular abnormalities, severe developmental delay, and structural brain anomalies. WMS3 is associated with pathogenic variants in the RAB18 gene, which affect vesicle trafficking and lipid metabolism. We report a 1.5-year-old female child, born to consanguineous parents, presenting with severe global developmental delay, hypotonia, delayed motor milestones, feeding difficulties, leukocoria, poor visual fixation, microcephaly, sensorineural hearing loss, bilateral dense cataracts, optic atrophy, and dyskinetic movements. Magnetic resonance imaging of the brain demonstrated agenesis of the corpus callosum, hypomyelination, and basal ganglia calcifications. Whole-exome sequencing revealed a homozygous likely pathogenic nonsense variant in RAB18 (c.306G>A; p.Trp102Ter), consistent with WMS3, along with a heterozygous variant of uncertain significance in PTPN23 . Multidisciplinary management was initiated, including neurorehabilitation, cataract surgery, auditory rehabilitation, nutritional support, and genetic counseling. This case highlights the classical phenotype of WMS3 and identifies a previously unreported truncating RAB18 variant (c.306G>A; p.Trp102Ter), which may expand the mutational spectrum of RAB18 -associated WMS.