What does Z-score and beta value mean in GWAS results?

Question

[Jerry]

"Beta coefficients are the estimates resulting from a regression analysis where the underlying data have been standardized so that the variances of dependent and independent variables are equal to 1." "Z-score is the number of standard deviations by which the value of a raw score (i.e., an observed value or data point) is above or below the mean value of what is being observed or measured."

In GWAS results, the SNPs are coded 0,1,2. So what does a beta of 0.1 means? When SNP rise for 1 SD, phenotype change for 0.1 SD? How can SNP rise for 1 SD? And what does a Z-score of 0.1 means?

Answer 1

[Jeremy Leipzig]

a beta coefficient of 0.1 means one copy of the allele is is associated with a 0.1 unit increase in the trait of interest