Posterior microphthalmos as a genetically heterogeneous condition that can be allelic to nanophthalmos.

P osterior microphthalmos (PM) is a rare developmental defect in which affected eyes display vitreous chamber foreshortening, normal or nearly normal anterior chamber depth, and papillomacular retinal folds. While membrane-type frizzled-related protein gene (MFRP [RefSeq NM_031433]) mutations have been reported to cause severe hyperopia that resembles PM, the resulting phenotype is better characterized as nanophthalmos owing to the involvement of the anterior chamber. Therefore, a genetic cause for PM remains elusive. Herein, we report the molecular analysis of 7 families with PM, which, in addition to narrowing a previously reported locus, establishes for the first time to our knowledge MFRP mutations as a cause of PM.