In genome-wide association studies, genome-wide significance (abbreviated GWS) is a specific threshold for determining the statistical significance of a reported association between a given single-nucleotide polymorphism (SNP) and a given trait.
[1] If a p-value is found to be lower than this threshold in a genome-wide association study, the null hypothesis of no true SNP-association will typically be rejected.
[2] However, there has been some criticism of this threshold, with a 2012 study suggesting that a significant number of associations with p-values just above this threshold are genuine, replicable associations.
The authors of this study concluded that their finding "...suggests a possible relaxation in the current GWS threshold.
"[3] More recently, it has been suggested that the conventional threshold should be modified to take into account the increasing prevalence of low-frequency genetic variants in genome-wide association studies.