Knobloch Syndrome - Triad of Occipital Encephalocele, Retino-Choroidal Detachment and Epilepsy

To the Editor: A 10-y-old boy born out of non-consanguineous marriage presented with occipital swelling since birth, drug-refractory seizures [generalized tonic-clonic seizures (GTCS)], and progressive loss of vision from 5 y of age. His younger sibling, an 8-y-old girl, presented with occipital swelling since birth, progressive vision loss, and seizures (GTCS) from 6 y of age. Common dysmorphic features were wide nasal bridge, smooth philtrum, and abnormal plantar creases. On examination, patient-1 had a healed scar in the occipital region, with a defect in the skull table on palpation. Ophthalmological examination of patient-1 showed complicated bilateral cataracts and phthisis bulbi (left). B-Scan ocular ultrasonography revealed bilateral retino-choroidal detachment. Magnetic resonance imaging (MRI) Brain and Orbits revealed bilateral frontal polymicrogyria, retinal detachment and bilateral cataracts. Ophthalmological examination of patient-2 showed retinal detachment (right) and phthisis bulbi (left). MRI Brain and Orbits revealed bilateral frontal polymicrogyria with right retinal detachment. Next-generation sequencing revealed homozygous single base pair deletion in exon 2 of COL18A1 gene (chr21:g.45405406deldel), resulting in frameshift and premature truncation of protein (p.Arg14AlafsTer110; ENST00000651438.1), suggestive of Knobloch syndrome-1 (KNO1). …