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Optimage health santa cruz3/21/2023 As part of quality control, SNPs were excluded if they had a call rate ≤97%, a minor allele frequency (MAF) ≤0.05, or significant deviations from Hardy-Weinberg equilibrium (HWE) ( P ≤ 10 −6). 21 In total, this panel has complete information for 2.6 million single nucleotide polymorphisms (SNPs), of which up to 874,733 SNPs are directly genotyped (HumanHap300: 303,940 SNPs HumanHap610Q: 553,487 SNPs and HumanHap1M and 1.2M: 874,733 SNPs) for all individuals. The imputation was performed with reference to HapMap (, available in the public domain by the International HapMap project) release 22 CEU (Utah residents with Northern and Western European ancestry from the CEPH collection) using IMPUTE version 2. Genotyping was carried out using a combination of Illumina arrays (Illumina, Inc., San Diego, CA): HumanHap 300k Duo HumanHap 610-Quad, and 1M-Duo and 1.2M-Duo. Absolute cylinder ranged between 0 and 4 D, and the mean was 0.38 D (☐.01) (Supplementary Table S1 ). The distribution of absolute cylinder was similar to the one used in the other cohorts, leptokurtic distribution with a right skew of 2.8. The normalized value, after applying the inverse normal transformation, of the absolute of the mean cylinder of both eyes was used for analysis. Subjects underwent cycloplegia (following instillation of tropicamide 1%), and refraction for both eyes was measured using a Humphrey-598 automatic refractor (Carl Zeiss Meditec, Inc., Miami, FL). Ethical approval was obtained from the Royal Victorian Eye and Ear Hospital, University of Tasmania, Australian Twin Registry, and Queensland Institute of Medical Research and adhered to tenets of the Declaration of Helsinki. In total this study included 1809 subjects from 786 families, 18 years old or older at the time of the examination. The Australian Twin Eye study included subjects examined as part of the Twin Eye Study in Tasmania and the Brisbane Adolescent Twin Study, between 20. Astigmatism presented a leptokurtic distribution with a right skew of 2.48 (Supplementary Table S1 ). Mean astigmatism was 0.76 diopters (D) (☐.69) with a range of 0 to 6.625. Here we decided to use absolute cylinder value rather than polar value as the former is an untransformed value and, thus, a direct measure of cylinder power and includes all types of astigmatism, not only with-the-rule (WTR) and against-the-rule (ATR) astigmatism but also oblique astigmatism, in contrast to the polar value, which is a transformed value 19 and excludes oblique astigmatism (transforms oblique astigmatism to values of zero). The astigmatism was calculated as the absolute value of cylinder (Ast = |cylinder|), and a posteriori, it was normalized by applying the inverse normal transformation. 12 An automatic refractor measures refractive error by detection of infrared light aligned through the pupil and reflected back by the retina. This finding advances the understanding of refractive error, and provides new potential pathways to be evaluated with regard to the development of astigmatism.Īll twin pairs underwent nondilated refraction using a Humphrey-670 (Humphrey Instruments, San Leandro, CA) automatic refractor (1998–2002) and subsequently an ARM-10 autorefractor (Takagi Seiko, Japan). Animal studies have shown a gradient in astigmatism along the vertical plane, with corresponding changes in refraction, particularly in the ventral field. VAX2 plays an important role in the development of the dorsoventral axis of the eye. We performed a meta-analysis of seven genome-wide association studies that included 22,100 individuals of European descent, where astigmatism was defined as the number of diopters of cylinder prescription, using fixed effect inverse variance-weighted methods.Ī susceptibility locus was identified with lead single nucleotide polymorphism rs3771395 on chromosome 2p13.3 (meta-analysis, P = 1.97 × 10 −7) in the VAX2 gene. This study aimed to identify susceptibility loci for astigmatism. Twin studies of astigmatism have found approximately 60% of phenotypic variance is explained by genetic factors. It is a complex trait likely to be influenced by both genetic and environmental factors. Astigmatism is a common refractive error that reduces vision, where the curvature and refractive power of the cornea in one meridian are less than those of the perpendicular axis.
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