Genome-wide association studies (GWAS) for refractive astigmatism and corneal astigmatism have identified a single locus for each; in the promoter of PDGFRA (4q12) for corneal astigmatism (Fan et al. 2011; Guggenheim et al. 2013; Shah et al. 2018) and near NRXN1 (2p16.3) for refractive astigmatism (Li et al. 2015). The gene discussed is NRXN1; the disease is Corneal astigmatism.