so the same reference panel may not be appropriate across the board. It will be interesting to study and potentially extend Vilhjálmsson et al. (2015)’s approach to admixed populations, despite the lack of training and testing samples with the same LD structure. Recently, Baker et al. (2018) proposed POLARIS, a method to construct PRSs while accounting for LD structure in the test dataset (i.e. not in a reference panel). It is a topic for future research to study the POLARIS approach for admixed and diverse populations. Other investigators worked on incorporating information from large studies in EA populations and a smaller admixed population, specifically focusing on trait prediction. Márquez-Luna et al. (2017) considered an approach that constructs a prediction model based on two PRSs, each constructed based on GWAS in a different population (EA and admixed population), and principal components of ancestry. They used either a validation dataset or cross validation to select LD parameters for clumping, p-value threshold for SNP selection, and also to select parameters for combining the two PRSs. We performed analyses mimicking their approach, by dividing the HCHS/SOL dataset to obtain training and validation datasets. However, this approach did not perform well, as determined by variance
