Two siblings with GAPO syndrome: Ophthalmic presentation and histopathologic findings

GAPO syndrome (growth retardation, alopecia, pseudoanodontia, optic atrophy) is a rare, autosomal recessive connective tissue disorder with only 60 reported cases. Ophthalmic manifestations vary and include hypertelorism, optic atrophy, and glaucoma. There have been three reported cases of GAPO syndrome with craniosynostosis.We describe two new siblings with GAPO syndrome and craniosynostosis and the first histopathologic analysis of Tenon's capsule and extraocular muscle in this syndrome.Both siblings presented with papilledema and V-pattern strabismus in addition to the alopecia, brittle eyelashes, growth retardation, and pseudoanodontia that characterize GAPO syndrome. Cranial vault expansion, though successful, was complicated by lack of distinct periosteal layers, thin dural adherence to bone, and extensive venous bleeding. Tenons encountered during strabismus surgery was inelastic and highly vascular. Histopathological analysis revealed hyalinization of Tenon's and a thickened, homogenized, amorphous appearance, similar to the extracellular matrix abnormalities described in skin and other organs Histopathological analysis of extraocular muscle was, in contrast, unremarkable.GAPO impacts the extracellular matrix of Tenon's resulting in inelasticity and hypervascularity. Ophthalmologists should be mindful of these aberrant characteristics when planning surgery in this population.