Genetics Expanding the Phenotypic and Genotypic Landscape of Nonsyndromic High Myopia: A Cross-Sectional Study in 731 Chinese Patients
Xue-Bi Cai,1 Yi-Han Zheng,1 De-Fu Chen,1 Fang-Yue Zhou,1 Lu-Qi Xia,1 Xin-Ran Wen,1 Yi-Min Yuan,1 Fang Han,1 Shun-Yu Piao,2 Wenjuan Zhuang,2 Fan Lu,1 Jia Qu,1 A-Yong Yu,1 and Zi-Bing Jin1 1The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, National Center for International Research in Regenerative Medicine and Neurogenetics, National Clinical Research Center for Ophthalmology, State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, China 2Ningxia Medical University, People’s Hospital of Ningxia Hui Autonomous Region, Yinchuan, China
Correspondence: Zi-Bing Jin, The PURPOSE. High myopia (HM) is defined as a refractive error worse than 6.00 diopter (D). This Eye Hospital, Wenzhou Medical Uni- study aims to update the phenotypic and genotypic landscape of nonsyndromic HM and to versity, Wenzhou 325027, China; establish a biological link between the phenotypic traits and genetic deficiencies. [email protected]. A-Yong Yu, The Eye Hospital, Wenz- METHODS. A cross-sectional study involving 731 participants varying in refractive error, axial hou Medical University, Wenzhou length (AL), age, myopic retinopathy, and visual impairment. The phenotypic traits were 325027, China; analyzed by four ophthalmologists while mutational screening was performed in eight [email protected]. autosomal causative genes. Finally, we assessed the clinical relevance of identified mutations Jia Qu, The Eye Hospital, Wenzhou under the guidance of the American College of Medical Genetics and Genomics. Medical University, Wenzhou 325027 China; RESULTS. The relationship between refractive error and AL varied in four different age groups [email protected]. ranging from 3- to 85-years old. In adult groups older than 21 years, 1-mm increase in AL Submitted: July 5, 2019 conferred 10.84% higher risk of pathologic retinopathy (Category ‡2) as well as 7.35% higher Accepted: August 19, 2019 risk of low vision (best-corrected visual acuities <0.3) with P values < 0.001. The prevalence rates of pathologic retinopathy and low vision both showed a nonlinear positive correlation Citation: Cai X-B, Zheng Y-H, Chen D-F, with age. Forty-five patients were confirmed to harbor pathogenic mutations, including 20 et al. Expanding the phenotypic and genotypic landscape of nonsyndromic novel mutations. These mutations enriched the mutational pool of nonsyndromic HM to 1.5 high myopia: a cross-sectional study in times its previous size and enabled a statistically significant analysis of the genotype– 731 Chinese patients. Invest Oph- phenotype correlation. Finally, SLC39A5, CCDC111, BSG, and P4HA2 were more relevant to thalmol Vis Sci. 2019;60:4052–4062. eye elongation, while ZNF644, SCO2, and LEPREL1 appeared more relevant to refracting https://doi.org/10.1167/iovs.19-27921 media.
CONCLUSIONS. Our findings shed light on how multiple HM-related phenotypes are associated with each other and their link with gene variants. Keywords: high myopia, gene, mutation spectrum, genotype-phenotype correlation
yopia is deemed the leading cause of vision impairment in CCDC111 (encoding the PRIMPOL protein), LRPAP1, SLC39A5, M many countries.1–3 Patients with high myopia (HM; a LEPREL1, P4HA2, and BSG.18–32 Female-limited nonsyndromic refractive error worse than 6.00 diopter [D]) tend to exhibit HM has been associated with two X-linked genes, OPN1LW and excessive elongation of the eyeball and thinning of the sclera, ARR3. causing irreversible changes of the eye both functionally and It is challenging to establish a network connecting multiple morphologically.4,5 An international grading system of photo- clinical features or to reveal a biological link between the graphic classification for myopic maculopathy has been phenotypic traits and genetic deficiencies of HM. Importantly, developed.6 According to a World Health Organization report, large samples with a wide range of refractive errors, axial HM is producing a heavy burden on public health care and lengths (AL), ages, categories of myopic retinopathy, and best- socioeconomic well-being worldwide.7 corrected visual acuities (BCVA) are required for analyzing HM is a complex trait determined by both environmental either the phenotypic variation or the genetic predisposition in and genetic factors.8 To date, less time for outdoor activities, HM patients. In our study, we recruited 731 sporadic higher education, urban living environment, and off-axis individuals with nonsyndromic HM and comprehensively refraction have been identified etiologically for HM.9–13 sequenced eight known autosomal causative genes. Finally, Twenty-five chromosomal loci and over 100 gene variants have we successfully interpreted the relationships between different been reported for myopia by linkage analysis, genome-wide clinical characteristics and simultaneously identified 29 patho- association studies, and next-generation sequencing.14–17 Cur- genic mutations in 45 index cases, including 20 novel rently, eight autosomal genes have been discovered as mutations. In combination with previous reports, we further replicable disease-causing genes of nonsyndromic HM across revealed the genotype–phenotype correlation from a world- different study populations, including ZNF644, SCO2, wide perspective. To our knowledge, this is the largest cohort
Copyright 2019 The Authors iovs.arvojournals.org j ISSN: 1552-5783 4052
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. Downloaded from iovs.arvojournals.org on 09/27/2021 Genotypic Landscape of Nonsyndromic High Myopia IOVS j September 2019 j Vol. 60 j No. 12 j 4053
with HM that has been both phenotypically and genetically TABLE 1. Information on Refractive Error, Axial Length, and Age in the studied. 731 Patients With High Myopia Age, y Number of METHODS Subjects 3~21 22~40 41~59 ‡60
Study Subjects All 731 97 232 250 152 The study was in line with the tenets of the Declaration of SE, D Helsinki and approved by Ethics Committee of the Eye Hospital 6.00 to 9.99 164 37 75 36 16 of Wenzhou Medical University. A group of 731 Chinese 10.00 to 13.99 211 37 70 59 45 individuals diagnosed with nonsyndromic HM and 1082 14.00 to 17.99 136 12 31 59 34 18.00 to 21.99 128 8 31 51 38 healthy controls were recruited for this study. Informed 22.00 92 3 25 45 19 consent was obtained from each participant. The examinations AL, mm of refractive error and BCVA were carried out by objective 25.01–27.00 160 41 68 33 18 refractometer (Nidek, Aichi, Japan) and subjective refractom- 27.01–29.00 247 41 88 72 46 eter. Spherical equivalent refractive errors (SE) were calculated 29.01–31.00 168 10 39 70 49 as the total of the spherical power plus half of the cylindrical 31.01–33.00 110 5 29 50 26 power. Patients with hyperopia or severe astigmatism ( 1.00 <