Female allele frequencies were determined using a randomly selected allele from each MAOA genotype. As human males are not diploid on the X chromosome, HWE was tested in the female genotypes. Male and female allele frequencies were then tested for significant differences in distribution as a populationlevel evaluation of HWE. Male genotypes (n = 578) from the VTSABD were obtained as part of a previously reported replication study of G × E in risk for CD among males (Foley et al. 2004).
