EPHA2 biallelic disruption causes syndromic complex microphthalmia with iris hypoplasia

Abstract

Disruption of any of the ocular development steps can result in ocular defects such as microphthalmia, coloboma and anterior segment dysgeneses including aniridia and cataract. All of these anomalies can be isolated or seen in association with each other. Except for aniridia (almost exclusively due to PAX6 mutations), most of these congenital ocular malformations are related to a wide genetic heterogeneity, as hundreds of genes are implied in ocular development. Here we describe a patient presenting with bilateral microphthalmia, congenital cataract, corneal dystrophy and iris hypoplasia, associated with extra-ocular features, who underwent an analysis of 119 ocular development related genes. Genetic testing revealed the presence of two truncating variants in the EPHA2 gene. While EPHA2 mutations are mainly known to be responsible for isolated dominant congenital cataract, we report here the first case of complex anterior segment dysgenesis caused by a biallelic EPHA2 mutation. This gene should be screened in case of aniridia with a negative PAX6 testing, as the ocular features of our patient clearly mimic those of PAX6 mutated patients. This observation enlarges the phenotype associated with EPHA2 variations and rise the insight of a possible PAX6-EPHA2 interaction that needs further investigations. Moreover, despite a great variability in ocular and extra-ocular phenotypes, mutations type and inheritance pattern, a possible genotype-phenotype correlation can also be drawn for this gene.