In genomewide association studies, meta-analysis has been key in establishing association between common variants and complex traits (Willer et al., 2010). Recent advances in exome sequencing and the development of exome genotyping arrays are enabling complex disease studies to explore association between rare variants of clear functional consequence and complex traits. For these rare variants, single variant tests can lack power, and association tests that group rare variants by gene or functional unit are favored (Li and Leal, 2008; Lin and Tang, 2011; Madsen and Browning, 2009; Price et al., 2010; Wu et al., 2011).
