The CREAM consortium conducted genome-wide meta-analyses, which identified 16 new loci for refractive error in individuals of European ancestry and 8 were shared with Asians, and identified 8 additional associated loci.
Abstract:
Refractive error is the most common eye disorder worldwide and is a prominent cause of blindness Myopia affects over 30% of Western populations and up to 80% of Asians The CREAM consortium conducted genome-wide meta-analyses, including 37,382 individuals from 27 studies of European ancestry and 8,376 from 5 Asian cohorts We identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians Combined analysis identified 8 additional associated loci The new loci include candidate genes with functions in neurotransmission (GRIA4), ion transport (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2 and BMP2) and eye development (SIX6 and PRSS56) We also confirmed previously reported associations with GJD2 and RASGRF1 Risk score analysis using associated SNPs showed a tenfold increased risk of myopia for individuals carrying the highest genetic load Our results, based on a large meta-analysis across independent multiancestry studies, considerably advance understanding of the mechanisms involved in refractive error and myopia
releasing factor 1) was also replicated in the meta-analysis (rs4778879;
P
combined
= 4.25 × 10
−11
)
9
. The remaining 16 loci associated at genome-
wide significance had not previously been reported in association
with refractive error. Those loci that did not show significant asso-
ciation in the smaller sized Asian population mostly had a similar
effect size and direction of effect as in the European ancestry sample.
In stage 3, we identified eight additional loci with associations
that exceeded genome-wide significance in the combined analysis
(Table 2). Regional and forest plots of the associated loci are provided
in Supplementary Figures 2 and 3, respectively.
Genotype distributions of the risk alleles were evaluated in
Rotterdam Studies 1–3 (n = 9,307). The clinical usefulness for the
prediction of risk of myopia was evaluated by a weighted genetic risk
score analysis based on the aggregate of effects (
β
regression coeffi-
cients) of individual SNPs derived from the meta-analysis, using the
middle risk category as a reference. Risk scores ranged from a mean
risk score of 1.88 (95% confidence interval (CI) = 1.86–1.89) in the
lowest risk score category to 3.63 (95% CI = 3.61–3.65) in the highest
risk score category. Having the lowest or the highest genetic risk score
was associated with an odds ratio (OR) of 0.38 (95% CI = 0.18–0.77)
and an OR of 10.97 (95% CI = 3.73–31.25) of myopia, respectively
(Fig. 2). The predictive value (area under the receiver operating
characteristic curve, AUC) of myopia versus hyperopia was 0.67
(95% CI = 0.65–0.69), a relatively high value for genetic factors in a
complex trait
13,14
. The genetic variants explained 3.4% of the pheno-
typic variation in refractive error in the Rotterdam Study.
We examined the expression of genes harboring a genetic asso-
ciation signal by measuring the levels of RNA in various eye tissues
and found most of these genes expressed in the eye (Supplementary
Table 3). Expression data for the PRSS56, LOC100506035 and SHISA6
genes were not available; all other genes were expressed in the
retina. Subsequently, we assessed the areas with associated SNPs
for acetylation at histone H3 lysine 27 (H3K27ac) modifications
15
and HaploReg
16
annotations for marks of active regulatory elements
(Supplementary Fig. 4 and Supplementary Table 4). We found that
many associated loci contained these elements, and alteration of regu-
latory function is therefore a potential mechanism.
The widely accepted model for myopia development is that eye
growth is triggered by a visually evoked signaling cascade, which
originates from the sensory retina, traverses the retinal pigment
epithelium (RPE) and choroid and terminates in the sclera, where
active extracellular matrix (ECM) remodeling results in a relative
elongation of the eye
17
. Many of the genes in or near the identified
loci can be linked to biological processes that drive this cascade.
Neurotransmission in the retina is a necessary mechanism for eye
growth regulation; the most significantly associated gene GJD2 has
a role in this process. This gene forms a gap junction between neu-
ronal cells in the retina, enabling the intercellular exchange of small
molecules and ions. The other previously reported gene RASGRF1 is a
nuclear exchange factor that promotes the exchange of GTP for GDP
on Ras family GTPases and is involved in the synaptic transmission
of photoreceptor responses
18,19
. Both GJD2 and RASGRF1knock-
out mice show retinal photoreception defects
18,20
. One of the newly
Table 1 Genome-wide significant associations with refractive error in the European ancestry population with results in the Asian population and combined analysis
Summary of SNPs that showed genome-wide significant (P < 5 × 10
−8
) association with spherical equivalent (SE) in subjects of European ancestry (stage 1), with results of replication in Asians (stage 2) and combined analysis
(stage 3). We tested for heterogeneous effects between the Asian and European ancestry samples, for which P values are shown. Nearest gene, reference NCBI build 37; A1, reference allele; A2, other allele, MAF, average minor allele frequency;
Summary of SNPs that showed genome-wide significant (P < 5 × 10
−8
) association with spherical equivalent in the combined analysis (stage 3), with results in subjects of European ancestry (stage 1) and Asians
(stage 2). We tested for heterogeneous effects between the two ancestry groups, for which P values are shown. Nearest gene, reference NCBI build 37. The RBFOX1 gene is also known as A2BP1.
0
5.00
10.00
15.00
20.00
25.00
30.00
<2.00
2.00–2.25
2.25–2.50
2.50–2.75
2.75–3.00
3.00–3.25
3.25–3.50
>3.50
Geneticrisk score
Subjects (%)
0
2.00
4.00
6.00
8.00
10.00
ORof myopia
OR of myopia
Myopia (%)
Emmetropia (%)
Hyperopia (%)
Figure 2Genetic risk score for myopia. Distribution of subjects from
Rotterdam Study 1–3 (n = 9,307) with myopia (SE ≤ −3 diopters (D)),
emmetropia (SE ≥ −1.5 D and ≤ 1.5 D) and hyperopia (SE ≥ 3 D) as a function
of the genetic risk score. This score is based on the regression coefficients
and allele dosages of the associated SNPs for all 26 loci identified in the
meta-analysis. Mean OR of myopia was calculated per risk category, using the
middle risk score category (risk score of 2.50–2.75) as a reference.
TL;DR: A use case of HaploReg is illustrated for attention deficit hyperactivity disorder (ADHD)-associated SNPs with putative brain regulatory mechanisms, and the number of chromatin state maps to 127 reference epigenomes is greatly expanded.
TL;DR: Combining increased time outdoors in schools, to slow the onset of myopia, with clinical methods for slowing myopic progression, should lead to the control of this epidemic, which would otherwise pose a major health challenge.
TL;DR: In this paper, the authors show that in the absence of population structure and other technical artefacts, but in the presence of polygenic inheritance, substantial genomic inflation is expected, its magnitude depends on sample size, heritability, linkage disequilibrium structure and the number of causal variants.
TL;DR: New therapeutic approaches including intravitreal injections of anti-vascular endothelial growth factor agents and the advance of vitreoretinal surgeries have greatly improved the prognosis of patients with pathologic myopia.
TL;DR: Myopia is becoming more common in Europe; although education levels have increased and are associated with myopia, higher education seems to be an additive rather than explanatory factor.
TL;DR: The Encyclopedia of DNA Elements project provides new insights into the organization and regulation of the authors' genes and genome, and is an expansive resource of functional annotations for biomedical research.
TL;DR: The Gene Expression Omnibus (GEO) project was initiated in response to the growing demand for a public repository for high-throughput gene expression data and provides a flexible and open design that facilitates submission, storage and retrieval of heterogeneous data sets from high-power gene expression and genomic hybridization experiments.
TL;DR: There is no obvious downside to using RMA and attaching a standard error (SE) to this quantity using a linear model which removes probe-specific affinities, and the exploratory data analyses of the probe level data motivate a new summary measure that is a robust multi-array average (RMA) of background-adjusted, normalized, and log-transformed PM values.
TL;DR: The Encyclopedia of DNA Elements project provides new insights into the organization and regulation of the authors' genes and genome, and is an expansive resource of functional annotations for biomedical research.
TL;DR: METAL provides a computationally efficient tool for meta-analysis of genome-wide association scans, which is a commonly used approach for improving power complex traits gene mapping studies.
The authors also confirmed previously reported associations with GJD2 and RASGRF1.
Q2. What is the role of Ras-GRF in the retina?
Expression of Ras-GRF in the SK-N-BE neuroblastoma accelerates retinoic-acid-induced neuronal differentiation and increases the functional expression of the IRK1 potassium channel.
Q3. What was the purpose of this study?
Subcellular localization assignment and functional annotation of myopiaassociated disease genes as well as molecular pathway analysis were carried out using the Ingenuity knowledge database (IPA).
Q4. what is the role of retinoic acid in the development of the eye?
J.R. & Wallman, J. Choroidal retinoic acid synthesis: a possible mediator between refractive error and compensatory eye growth.
Q5. What were the criteria used to filter SNPs with low imputation quality?
SNPs with low imputation quality were filtered using metrics specific to the imputation method and thresholds used in previous GWAS analyses.
Q6. What was the significance of the signal intensities of the probes?
For each tissue type, the probes with signal intensities below background levels and those with the lowest (5%) signal intensities (detection P < 0.10) were excluded.
Q7. What was the mean value of the spherical equivalent?
Spherical equivalent was calculated according to the standard formula (SE = sphere + 1/2 cylinder), and the mean value from two eyes was used for analysis.
Q8. How many individuals were included in the meta-analysis?
The authors performed a meta-analysis on directly genotyped and imputed SNPs from individuals of European ancestry in 27 studies, with a total of 37,382 individuals.
Q9. What was the function used to find the potential functional relationships between the myopia-associated genes?
the authors used the IPA ‘connect’ function to discover potential direct or indirect functional relationships or molecular pathways in between these entries.
Q10. How long did the globes stay in the ice?
All whole globes were immersed in RNALater (Qiagen) within 6.5 h of collection, shipped overnight on ice and dissected on the day of arrival.
Q11. What was the significance of the meta-analyses?
For the Rotterdam Study 1–3, a weighted genetic risk score per individual was calculated using the regression coefficients from the GWAS meta-analysis model for the association of SNPs within the associated 26 loci (Tables 1 and 2; for each locus, only one SNP was included in the analysis) and the individual allele dosages per genotype to evaluate the relationships between myopia (SE ≤ −3 D), emmetropia (–1.5 D ≤ SE ≤ 1.5 D) and hyperopia (SE ≥ 3 D).
Q12. Where is the Netherlands Institute of Neurosciences?
54Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute of Neurosciences (NIN; an Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands.