Despite considerable recent progress, there are some areas where further research on summary statistic based methods is needed. As population reference panels grow, more accurate modeling of rare and low-frequency variants will become possible, and it will be important to assess the limits of such efforts. It is also of interest to develop methods for inferring polygenic architectures from summary statistics that allow for different relationships between allele frequency and effect size. Identifying functional annotations that are enriched for heritability is an application that is particularly likely to produce important biological insights, and here there is a need for new methods that are well-powered for functional categories spanning a small percentage of the genome. As the number of functional annotations continues to increase, the integration of such data poses computational and statistical challenges in disentangling the correct functional annotations among many correlated ones.
