Toward Novel Diagnostics for Primary Open-Angle Glaucoma? An Association Study of Polymorphic Variation in Ras Homolog Family Member (A, B, C, D) Genes RHOA, RHOB, RHOC, and RHOD

The annual economic burden of visual disorders in the United States was estimated as $139 billion. The World Health Organization has listed glaucoma in the top 10 priority eye diseases. Primary open-angle glaucoma (POAG) is a common subtype, with a lack of clinical tools for early diagnosis. The Rho GTPases belong to the Ras superfamily of proteins; the RhoA immunostaining in the optic nerve head in human glaucoma is reportedly increased. We investigated the association of polymorphisms in the Ras Homolog Family Member A, B, C, and D genes ( RHOA , RHOB , RHOC , and RHOD , respectively). In a total sample of 361 unrelated subjects (179 patients with POAG and 182 age- and sex-matched healthy controls), RHOA (rs6784820, rs974495), RHOB (rs62121967), RHOC (rs11102522), and RHOD (rs61891303, rs2282502) polymorphisms were characterized by the BioMark HD dynamic array system with real-time polymerase chain reaction. Among these candidate genetic markers and considering the Bonferroni correction, RHOA rs974495 polymorphism was significantly associated with POAG ( p = 0.0011), with the TT genotype increasing the disease risk 4.9 times (95% CI 1.630–15.023). The allele and haplotype distributions of the above RHO candidate polymorphisms did not display a significant association. This is the first study, to the best of our knowledge, to identify a significant genotypic association between POAG and RHOA gene rs974495 polymorphism. These observations warrant replication in independent samples in the pursuit of precision medicine for rapid and early glaucoma diagnosis, and molecular targets for innovation in therapeutics of this common eye disease.