Hereditary colobomatous anomalies of the optic nerve head.

The authors describe a family showing coloboma of the optic nerve associated with chorioretinal coloboma and coloboma of the iris. The absence of its occurrence in association with extraocular malformations points to an autosomal dominant mode of transmission, with reduced penetration. The authors describe the probable pathogenetic mechanism of the disorder and discuss the differential diagnosis both for chorioretinal coloboma (inflammatory chorioretinitis, especially by toxoplasma) and for colobomas of the optic disc (papillary pits and morning glory syndrome). The molecular basis of the malformation is however still unknown and thus a prenatal diagnosis is impossible.