Locus 1 (15q14). We completed a GWAS for the phenotype 'refractive error' in our Discovery cohort, the population-based Rotterdam Study (N = 5,328 subjects, using SNPs genotyped with the Illumina Infinium II HumanHap550 chip v3.0 array) . The results were replicated in 4 additional cohorts (combined N = 10,280 individuals in the replication stage): the Rotterdam Study II cohort, the Rotterdam Study III cohort, the Erasmus Rucphen Family (ERF) Study cohort and the TwinsUK cohort. The findings have been reported [1].

Locus 2 (15q25). In collaboration with the TwinsUK group, a second region of strong association was observed at 15q25. This association was replicated in a combined sample comprising the above cohorts, along with subjects from the 1958 British Birth Cohort and the Australian Twin Eye Study cohort (combined N = 13,414 subjects). These findings have also been published [2].

We propose to carry out additional replication studies for 19 SNPs in these two regions of strong association in a number of cohorts of European ethnicity. The ALSPAC cohort is suitable because it is ethnically well-matched to our original study cohort and is also a population-based sample, not selected based on eye phenotypes. We expect this will aid the differentiation of causal variants and non-causal variants in the associated regions.

Replication analysis on the 19 SNPs will be performed by Dr Jez Guggenheim, who is part of the ALSPAC Myopia team, and summary results will be sent to Dr Virginie J.M. Verhoeven. To facilitate the replication step on the ALSPAC side, we ask for a DTA of the 19 SNPs to Dr Jez Guggenheim who will perform the work at Cardiff University, or in Bristol if required.