RESUMO
Background: Congenital Stationary Night Blindness (CSNB) is a clinically and genetically heterogenous inherited retinal disorder associated with nystagmus, myopia, strabismus, defective dark adaptation, and decreased vision. Pathogenic variants in at least 17 genes have been associated with CSNB, where a hemizygous variant of NYX causing an X-linked form of the disorder is among the commonest causes.Materials and Methods: A retrospective chart review of a single pedigree was performed. Three pediatric patients underwent ophthalmic examinations, visual electrophysiology, and ocular imaging. Molecular genetic testing for CSNB was pursued where clinically indicated.Results: Two male siblings demonstrated clinical and electroretinographic evidence of complete CSNB. Genetic testing identified a NYX pathogenic, in-frame deletion in both children. Targeted variant analysis of the mother failed to identify the variant in two independent samples, most consistent with mosaicism.Conclusions: Clinical and molecular analyses within the described family demonstrate the possibility of maternal mosaicism in NYX-related CSNB. The importance of cascade molecular testing is highlighted. The prospect of somatic or germline mosaicism in NYX-related CSNB informs genetic counseling, genetic testing decisions, and risk assessment in affected families.
Assuntos
Oftalmopatias Hereditárias/genética , Deleção de Genes , Doenças Genéticas Ligadas ao Cromossomo X/genética , Mosaicismo , Miopia/genética , Cegueira Noturna/genética , Proteoglicanas/genética , Adulto , Criança , Pré-Escolar , Eletrorretinografia , Oftalmopatias Hereditárias/diagnóstico , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico , Testes Genéticos , Genótipo , Humanos , Lactente , Masculino , Miopia/diagnóstico , Cegueira Noturna/diagnóstico , Linhagem , Estudos Retrospectivos , Irmãos , Tomografia de Coerência ÓpticaRESUMO
Anterior segment ischemia (ASI) is a potentially serious but rare complication of strabismus surgery. Among several risk factors, ASI occurs after strabismus surgery because of the nature of the anterior segment circulation. Disinsertion of rectus muscles leads to a decrease in the blood supply to the various anterior segment structures. We report a series of retrospective and prospective studies performed by our group focused on determining the risk of anterior segment ischemia following strabismus surgery, diagnosis, and modifications to surgical techniques to minimize the impact on anterior segment circulation. We found a significant decrease in postoperative anterior segment blood flow when operating vertical rectus muscles. Plication procedures preserve anterior segment circulation, and modifications to the technique allow the performance of adjustable sutures. Small adjustable selective procedures that spare the ciliary vessels have been demonstrated to be effective in patients with vertical and torsional diplopia. Ciliary sparing augmented adjustable transposition surgery decreases the risk of anterior segment ischemia while allowing management of potential post-operative alignment complications. Finally, ocular coherence tomography angiography is a valuable quantitative and qualitative technique to evaluate anterior segment ischemia. Strabismus surgeons should be aware of the risks of anterior segment ischemia when operating vertical rectus muscles. Modifications to standard surgical techniques allow surgeons to perform complex strabismus surgery in patients at risk for anterior segment ischemia.
