Final answer:
GWAS alone cannot predict the aggregate effect of multiple SNPs on a trait or estimate an individual's genetic predisposition to certain traits, whereas using GPS allows for these complex analyses.
Step-by-step explanation:
When exploring allele-trait associations, Genome-wide Association Studies (GWAS) have provided significant insights since their advent in 2005. Nonetheless, there are complex analyses that GWAS alone cannot accomplish. By utilizing Genomic Prediction Scores (GPS), researchers can delve deeper into the association between alleles and traits to discover intricate details not achievable solely with GWAS.
Firstly, GPS can help predict the aggregate effect of multiple SNPs on a given trait, a task difficult for GWAS as it usually identifies single SNP-trait associations. Secondly, GPS facilitates the estimation of the genetic predisposition of an individual to a certain trait or disease, which GWAS alone cannot determine as precisely since GWAS primarily provides statistical associations rather than a predictive outlook.