In GWAS studies, 5*10-8 seems the defacto standard for association. A lesser known threshhold is 1*10-5.

This threshhold is often called "suggestive association."

I am writing to ask, where did this figure come from? Were empirical tests or statistical simulations done to select this level?

I can find many papers that USE this level, but far fewer that JUSTIFY it. Any relevant citations would be welcome, and thank you.
> "The P values of Bonferroni corrected thresholds for suggestive, 5 and
> 1% genome-wide significant levels were 1, 0.05 and 0.01, respectively,
> divided by the number of SNPs used in the GWAS. The suggestive level
> was first proposed by Lander and Kruglyak [17] and represents the
> threshold where, under the null hypothesis, one false positive is
> expected per genome scan."

So the suggestive line is calculated as the `-log10( 1 / number of variants) `

[Reference](https://www.ncbi.nlm.nih.gov/pubmed/28196480): Guo, Y., Huang, Y., Hou, L., Ma, J., Chen, C., Ai, H., ... & Ren, J. (2017). Genome-wide detection of genetic markers associated with growth and fatness in four pig populations using four approaches. Genetics Selection Evolution, 49(1), 21.