Occipital Cephalocele, Polymicrogyria, Ocular Anomaly and Vermian Dysplasia: Prenatal Markers for Knobloch Syndrome.

Knobloch Syndrome-1 is a rare autosomal recessive disorder typically diagnosed postnatally and characterized by occipital encephalocele, high myopia, and vitreoretinal degeneration. We describe a fetus with a constellation of prenatal neuroimaging findings, including occipital cephalocele, vermian dysplasia, bilateral polymicrogyria, and ocular elongation, that prompted genetic investigation. Trio exome sequencing identified biallelic pathogenic variants in COL18A1, confirming the diagnosis of Knobloch Syndrome-1. This case highlights how advanced fetal neuroimaging and prenatal exome sequencing can facilitate early recognition of syndromes like Knobloch, and underscores the importance of considering COL18A1-related disorders when multiple central nervous system anomalies are detected prenatally.