Correlations in refractive errors between siblings in the Singapore Cohort Study of Risk factors for Myopia

School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales CF10 3NB, UK.
British Journal of Ophthalmology (Impact Factor: 2.98). 06/2007; 91(6):781-4. DOI: 10.1136/bjo.2006.107441
Source: PubMed


The prevalence of myopia in parts of South East Asia has risen dramatically over the past 1-2 generations, suggesting that environmental factors may be particularly important determinants of refractive development in these populations.
To assess the contribution of familial factors (shared genes and/or shared family environment) to refractive error and ocular component dimensions of school-aged children in Singapore.
Data were available for 315 children who had one or more siblings also participating in the Singapore Cohort Study of the Risk factors for Myopia (SCORM). Refractive error and ocular biometric parameters were measured under cycloplegia at baseline when children were 7-9 years, and at yearly follow-up sessions for the next 3 years, using consistent clinical procedures. The time children spent performing a variety of nearwork-related tasks was obtained from questionnaires. Familial influences were assessed by calculating between-sibling correlations.
After adjusting for age and sex, the between-sibling correlation in refractive error was 0.447 (95% CI 0.314 to 0.564), suggesting that familial factors account for 63-100% of the variation in the cohort. The between-sibling correlation for 1-year change in refractive error was similarly high, at 0.420 (95% CI 0.282 to 0.543). All ocular component dimensions were correlated significantly between siblings, especially for corneal curvature and vitreous chamber depth--the major structural determinants of refraction. The amount of time siblings spent engaged in nearwork tasks (reading, watching TV, playing video games, computing) and in outdoor activities was also highly correlated between siblings (p<0.001).
Shared genes and/or shared environment are important factors in the refractive development of children in Singapore. Because the time spent in nearwork tasks is highly correlated between siblings, epidemiological studies will benefit from precise, quantitative measures of refractive error in parents and more distant relatives in order to begin to dissociate genetic and environmental sources of variation.

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    • "Moreover, higher heritability estimates have been reported in twin and sibling studies. Guggenheim et al.24 investigated correlations in refractive errors between siblings in a Singaporean cohort study and found a correlation in refractive error of 44.7% after adjusting for age and sex. A twin study undertaken by Dirani et al.18 showed that the effects of additive genes explained 58% and 47% of the variance for refractive error in the men and women, respectively. "
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    ABSTRACT: BACKGROUND Myopia is a very common condition and a significant public health problem in China. The objective of the study was to explore the genetic influence on myopia in Mainland China school-aged children in Beijing. METHODS In 2008, the data from 15,316 Chinese school students aged 6–18 years from 19 randomized schools in Beijing were analyzed to evaluate genetic influence on myopia in children. Heritability was calculated by mid-parent–offspring regression and parent–offspring regression. RESULTS The estimate of heritability was 0.30 (95% CI, 0.27–0.33) for refractive value (RV). The adjusted mean refractive error was −2.33D (95% CI, −2.45 to −2.21) in children with two myopic parents compared with −1.13D (95% CI, −1.78 to −1.08) in children with no parental myopia. The adjusted odds ratio (OR) was 2.83 (95% CI, 2.47–3.24) in children with two myopic parents compared with no parental myopia. CONCLUSION The study found a strong association between parental history of myopia and genesis of myopia in the offspring even after adjusting for environmental factors.
    Preview · Article · Jun 2014 · Opthalmology and Eye Diseases
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    • "Its extreme form, high myopia, is the fourth most common cause of irreversible blindness [6,7]. Evidence has demonstrated that genetic factors play an important role in the development of high myopia [1,8-11]. Molecular genetic investigations of high myopia have become a hot topic in recent years. "
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    ABSTRACT: EGR1 (OMIM 128990) is an early growth response gene that has been shown to be related to myopia by upregulation and down-regulation of axial eye growth in experimentally induced chicken myopia and knockout mice. The purpose of this study was to test whether variations in the human EGR1 gene are related to high myopia. Genomic DNA was prepared from leukocytes of peripheral blood. Cycle sequencing was used to detect sequence variations in EGR1. No pathological mutations were detected upon sequencing of the coding regions and the adjacent intronic regions of EGR1 in 96 unrelated Chinese subjects with high myopia. Only one silent variation, c.1026G>A (p.V342V), was detected in one patients with high myopia, which would not affect the encoded protein. For all 96 subjects, only one allele was detected in each of the three known single nucleotide polymorphisms (SNPs) in EGR1. We found no evidence that EGR1 is responsible for high myopia in these patients.
    Full-text · Article · Jul 2008 · Molecular vision
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