TITLE:
Genetic risk factors and retinal ganglion cell degeneration in primary open-angle glaucoma (POAG): A bird’s eye view
AUTHORS:
Barkur S. Shastry
KEYWORDS:
Degeneration, Gene, Mutation, Retina
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.4 No.5,
May
27,
2013
ABSTRACT: Glaucoma is an optic neuropathy
and often associated with elevated intraocular pressure (IOP). It is the second
leading cause of irreversible blindness worldwide and is characterized by the
optic nerve degeneration and loss of retinal ganglion cells (RGCs). This may
lead to loss of vision. The primary cause of glaucoma is unknown but several
risk factors including elevated IOP and age have been suggested. In most
population, primary open-angle glaucoma (POAG) is the most common type of
glaucoma and is often associated with elevated IOP. Genetic analyses have identified at least 14 chromosomal loci but only
three genes which when mutated can cause POAG have been well documented.
These genes account for less than 5% of all POAG cases suggesting that more
than 90% of the genetic contribution of POAG
cases is unknown. RGC consists of cell body, axon and dendritic arbor
and each of these three parts can independently degenerate. Several molecular
signals such as oxidative stress, mitochondrial dysfunction, disruption of neurotrophic
factor (NTF), dysfunction of immune system, glial activation and the release of
tumor necrosis factor (TNF) have been found to be involved in the optic nerve
degeneration. Therefore, therapies aimed at axonal and cell body protection may
have a greater protective role in early or progressive glaucoma. In the future,
an understanding of gene-gene and gene-environmental factor interaction as
well as epigenetic regulation of gene expression by environmental factors may
provide an opportunity to develop neuroprotective therapies and DNA based
diagnostic tests.