Genetic Basis of Primary Angle Closure Glaucoma: The Role of Collagens and Extracellular Matrix

Glaucoma is a heterogeneous group of optic neuropathies characterized by a specific pattern of optic nerve degeneration and visual field loss that is usually accompanied by increased intraocular pressure (IOP).[1] It is a major cause of irreversible blindness worldwide.[2] Primary glaucoma is classified into three major forms based on the anatomy of the anterior chamber drainage angle of the eye and the age of onset: primary congenital glaucoma (PCG), primary open angle glaucoma (POAG), and primary angle closure glaucoma (PACG).[1] In glaucoma patients with increased IOP, the increase is thought to be mainly due to impaired drainage of aqueous humor from the anterior chamber.[ The etiology of all forms of glaucoma includes a genetic component as evidenced by variable prevalence in different ethnic groups, observations on familial clustering, and results of pedigree and sib-pair studies. For PCG, which is usually a monogenetic Mendelian disease, three causative genes have been identified.[4–7] POAG and PACG are generally considered complex multifactorial disorders.[8] Several POAG-causing genes have been identified, but mutations in these account for disease in less than 10% of patients.