GWAS analyses of autosomes were conducted in each study using linear regression of standardised traits adjusted for the effects of sex, age and population stratification. Dosage analysis accounted for differential imputation quality of SNPs. In the CROATIA-Vis, CROATIA-Korcula and ORCADES cohorts, analyses were performed using the *ABEL suite of software (Aulchenko et al. 2007) making adjustments for pedigree structure. For the other cohorts, association analyses were performed in mach2qtl (Li et al. 2009). A weighted inverse variance method in METAL (Willer et al. 2010) was used to meta-analyse the results. A genome-wide significance level of P<5×10−8 (Dudbridge and Gusnanto 2008) and a suggestive significance level of 6.09×10−6 (Duggal et al. 2008) was adopted.
