Glaucoma is a major cause of blindness and is characterized by progressive degeneration of the optic nerve and is usually associated with elevated intraocular pressure. Analyses of sequence tagged site (STS) content and haplotype sharing between families affected with chromosome 1q-linked open angle glaucoma (GLC1A) were used to prioritize candidate genes for mutation screening. A gene encoding a trabecular meshwork protein (TIGR) mapped to the narrowest disease interval by STS content and radiation hybrid mapping. Thirteen glaucoma patients were found to have one of three mutations in this gene (3.9 percent of the population studied). One of these mutations was also found in a control individual (0.2 percent). Identification of these mutations will aid in early diagnosis, which is essential for optimal application of existing therapies.

Glaucoma is one of the most common neurodegenerative diseases. Despite this, the earliest stages of this complex disease are still unclear. This study was specifically designed to identify early stages of glaucoma in DBA/2J mice. To do this, we used genome-wide expression profiling of optic nerve head and retina and a series of computational methods. Eyes with no detectable glaucoma by conventional assays were grouped into molecularly defined stages of disease using unbiased hierarchical clustering. These stages represent a temporally ordered sequence of glaucoma states. We then determined networks and biological processes that were altered at these early stages. Early-stage expression changes included upregulation of both the complement cascade and the endothelin system, and so we tested the therapeutic value of separately inhibiting them. Mice with a mutation in complement component 1a (C1qa) were protected from glaucoma. Similarly, inhibition of the endothelin system with bosentan, an endothelin receptor antagonist, was strongly protective against glaucomatous damage. Since endothelin 2 is potently vasoconstrictive and was produced by microglia/macrophages, our data provide what we believe to be a novel link between these cell types and vascular dysfunction in glaucoma. Targeting early molecular events, such as complement and endothelin induction, may provide effective new treatments for human glaucoma.

The glaucomas are neurodegenerative diseases involving death of retinal ganglion cells and optic nerve head excavation. A major risk factor for this neurodegeneration is a harmfully elevated intraocular pressure (IOP). Human glaucomas are typically complex, progressive diseases that are prevalent in the elderly. Family history and genetic factors are clearly important in human glaucoma. Mouse studies have proven helpful for investigating the genetic and mechanistic basis of complex diseases. We previously reported inherited, age-related progressive glaucoma in DBA/2J mice. Here, we report our updated findings from studying the disease in a large number of DBA/2J mice. The period when mice have elevated IOP extends from 6 months to 16 months, with 8-9 months representing an important transition to high IOP for many mice. Optic nerve degeneration follows IOP elevation, with the majority of optic nerves being severely damaged by 12 months of age. This information should help with the design of experiments, and we present the data in a manner that will be useful for future studies of retinal ganglion cell degeneration and optic neuropathy.

TGFbeta2 effects on IOP may be transduced by TGFbeta type-I receptor-mediated changes in TM secretion of ECM-related factors such as fibronectin and PAI-1. Modulation of TGFbeta2-induced changes in the ECM may provide a novel and viable approach to the management of glaucoma.

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