Early-Onset Seizures Revealing 1p36 Deletion Syndrome in an Infant with Craniofacial Dysmorphism and Optic Disc Coloboma: A Case Report

Abstract

Aims: To describe an infant in whom early-onset seizures led to the diagnosis of 1p36 deletion syndrome and to emphasise the diagnostic contribution of whole-exome sequencing with copy-number variation analysis when the early phenotype is incomplete. Presentation of Case: A 2-month-old male infant was admitted for generalised clonic seizures with gaze fixation in an afebrile setting. Examination showed hypotonia and craniofacial dysmorphism. Electroencephalography demonstrated diffuse interictal epileptiform abnormalities with right frontal predominance, whereas brain magnetic resonance imaging was normal. Ophthalmological examination revealed an inferior optic disc coloboma of the left eye. Echocardiography was normal, while abdominopelvic ultrasound showed testicular ectopia. TORCH serologies were negative and the metabolic work-up was normal. Whole-exome sequencing with copy-number variation analysis identified a pathogenic heterozygous deletion of at least 9 Mb involving chromosome 1p, consistent with 1p36 deletion syndrome. Seizures ceased under sodium valproate. Discussion: 1p36 deletion syndrome has marked phenotypic variability, and epilepsy may begin in early infancy. A normal brain MRI or cardiac assessment does not exclude the diagnosis when seizures are associated with hypotonia and dysmorphic features. The optic disc coloboma in this patient should be considered an uncommon ocular finding rather than a specific manifestation. Exome-derived copy-number analysis can identify large deletions, but dedicated cytogenetic confirmation remains important for characterisation of the rearrangement and genetic counselling. Conclusion: 1p36 deletion syndrome should be considered in infants with unexplained early-onset seizures, hypotonia, craniofacial dysmorphism, and associated congenital anomalies. Early genetic diagnosis supports appropriate multidisciplinary follow-up and family counselling.