marginally significantp = 0.03
As extreme phenotype samples have been shown to increase power in genetic association studies [ 52 , 53 ], when emmetropic individuals were included in the control group, the association of rs634990 with myopia became smaller and marginally significant (heterozygous carriers: OR = 1.36 [1.03, 1.78], p = 0.03; homozygous carriers: OR = 1.48 [1.07, 2.04], p = 0.02).