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Angle-closure glaucoma (ACG) is a subset of glaucoma affecting 16 million people. Although 4 million people are bilaterally blind from ACG, the causative molecular mechanisms of ACG remain to be defined. High intraocular pressure induces glaucoma in ACG. High intraocular pressure traditionally was suggested to result from the iris blocking or closing the angle of the eye, thereby limiting aqueous humor drainage. Eyes from individuals with ACG often have a modestly decreased axial length, shallow anterior chamber and relatively large lens, features that predispose to angle closure. Here we show that genetic alteration of a previously unidentified serine protease (PRSS56) alters axial length and causes a mouse phenotype resembling ACG. Mutations affecting this protease also cause a severe decrease of axial length in individuals with posterior microphthalmia. Together, these data suggest that alterations of this serine protease may contribute to a spectrum of human ocular conditions including reduced ocular size and ACG. [ABSTRACT FROM AUTHOR]

Posterior microphthalmia (PM) is a relatively rare autosomal recessive condition with normal anterior segment and small posterior segment resulting in high hyperopia and retinal folding. It is an uncommon subtype of microphthalmia that has been mostly reported to coexist with several other ophthalmic conditions and to occur in sporadic cases. The membrane-type frizzled-related protein ( MFRP) is the only gene so far reported implicated in autosomal recessive, non-syndromic and syndromic forms of PM. Here, we performed a clinical and genetic analysis using six consanguineous families ascertained from different regions of Tunisia and affected with non-syndromic PM that segregates as an autosomal recessive trait. To identify the disease-causing defect in these families, we first analysed MFRP gene, then some candidate genes ( CHX10, OPA1, MITF, SOX2, CRYBB1-3 and CRYBA4) and loci (MCOP1, NNO1 and NNO2) previously implicated in different forms of microphthalmia. After exclusion of these genes and loci, we performed a genome-wide scan using a high density single nucleotide polymorphism (SNP) array 50 K in a large consanguineous pedigree. SNP genotyping revealed eight homozygous candidate regions on chromosomes 1, 2, 3, 6, 15, 17 and 21. Linkage analysis with additional microsatellite markers only retained the 2q37.1 region with a maximum LOD score of 8.85 obtained for D2S2344 at θ = 0.00. Further investigations are compatible for linkage of four more families to this region with a refined critical interval of 2.35 Mb. The screening of five candidate genes SAG, PDE6D, CHRND, CHRNG and IRK13 did not reveal any disease-causing mutation. [ABSTRACT FROM AUTHOR]