VDR and pertussis: When the pertussis patients with a duration of symptoms > 4 weeks were selected for VDR polymorphism distribution analysis (n = 176) compared with control group (n = 462), the association of the G:G genotype with symptomatic pertussis was increased (p = 0.012) (Table 5) compared to the total pertussis patient cohort (p = 0.046) (Table 2).