Ophthalmic manifestations of MAB21L2 mutation: A case report

Introduction: This report is to describe the clinical presentation, ophthalmic findings, and multimodal evaluation of a child with severe bilateral microphthalmia and coloboma associated with a MAB21L2 variant. Case Report: A 3-year-old girl presented with bilateral small eyes and abnormal eye movements. Examination showed chin-up posture, bilateral ptosis, large-angle non-accommodative esotropia, limitation of abduction, wandering nystagmus, xanthocoria on Bruckner test, microcornea [8 mm OD (right eye), 6.5 mm OS (left eye)), sclerocornea superiorly with clear central cornea, bilateral inferonasal iris coloboma, and inferior lens subluxation with zonular disruption. Fundus examination revealed a severely disorganized retina with retinal cysts and folds and inferior chorioretinal coloboma. Intraocular pressure (IOP) was 21 mmHg OD and 19 mmHg OS. A B-scan revealed taut retinal folds with a retinal cyst in the OD and a retinal cyst in the OS. Magnetic resonance imaging (MRI) orbit/brain showed small globes [measuring about 11–12 mm in anteroposterior diameter (AP)], with multiple retrobulbar cysts encroaching on the optic nerve sheath complex, bilateral optic nerve hypoplasia (T p.(Cys250Phe). Conclusion: This case illustrates a severe microphthalmia and coloboma spectrum disorder with extensive anterior and posterior segment dysgenesis and marked optic nerve hypoplasia. Serial examination under anesthesia (EUA) and multimodal imaging were of the essence for complete characterization and follow-up. The familial pattern and MAB21L2 finding provide a unifying developmental explanation for the case.