Genotype groups were then compared on age using t-tests and on gender using chi-squared tests. In addition, genotype group comparisons were conducted using Student’s t-tests for continuous variables, as t-tests account for potential violations of the assumption of the homogeneity of variance, an important issue when comparing 2 groups with an unequal number of participants (n). Specifically, for variables in which the homogeneity of variance assumption was held, results of t-tests using pooled variance are reported, whereas for variables that violated the homocedasticity assumption in our sample, the individual sample standard deviation was used to calculate the t-tests. Associations among continuous predictors were examined using Person product–moment correlations. Main outcome analyses were performed using SAS statistical software (SAS Institute, Inc., Cary, NC). For all comparisons, statistical significance was set at p < 0.05, and all tests were 2-tailed.
