Genetic susceptibility to primary angle closure glaucoma (PACG).

Glaucoma is a group of heterogeneous optic neuropathy and is the second leading cause of irreversible blindness worldwide. The two most common clinical types of glaucoma include primary open-angle (POAG) and primary angle-closure glaucoma (PACG). PACG is characterized by the closure of angles between iris and trabecular meshwork (iridocorneal angles) mainly because of anatomic abnormalities. The condition is more prevalent in Chinese, Asian Indians, and Eskimos. Because of an unusually high incidence of PACG among siblings of affected patients, it was suggested that genetic factors were involved in its pathology and the action of a large number of grouped or independently inherited genes along with environmental factors result in anatomical abnormalities of PACG. In PACG, the genetic basis is not well understood. Genome-wide association studies have identified several candidate genes in relation to PACG in several different populations. However, they are not reproduced from population to population or the results are controversial. This may indicate that the involvement of genetic abnormality in the pathogenesis of PACG is complex. The availability of spontaneously occurring large animal models such as dogs may provide an opportunity to identify genes responsible for the pathophysiology of PACG in the future. This article summarizes the current status of genetic investigations on PACG which is the most common cause of blindness worldwide.