This study uses data from a large national sample in Taiwan to examine these issues. By comparing the 5-HTTLPR genotype distribution in our study with other samples from different racial and ethnic groups, we underscore the large variation across populations. Our sample displays a much higher frequency of XL alleles than most previous studies, challenging the contention that the XL allele is rare. We examine GxE interactions with two types of stressors—recent major life events and lifetime trauma—on depressive symptoms among older adults, a segment of the population that has rarely been the focus of such studies [17]. We also explore whether the GxE interaction varies by sex. The estimates provide insight into the phenotype associated with the XL allele.
