Background: Streptococcal throat infections and HLA Cw6 (Cw*06) have been implicated in the pathogenesis of psoriasis, particularly in the guttate form.
Objectives: To study 105 Irish patients with psoriasis to investigate the relationship between streptococcal infections and Cw*06.
Methods: The patients were divided into two groups: those with guttate psoriasis or guttate flare (guttate group, GG, n=64) and those with chronic plaque psoriasis (chronic plaque group, CPG, n=41).
Results: The incidence of Cw*06 was 86% in the GG and 73% in the CPG, which was not significantly different (P=0.1725) but the incidence in both groups was significantly higher than in an Irish control group (18%) (P<0.0001 vs. GG and P<0.0001 vs. CPG). Evidence for streptococcal infection was higher in the GG (56%) than in the CPG (32%) (P=0.0231). Of those patients with evidence of streptococcal infection, 30 of 36 GG (83%) and nine of 13 CPG (69%) patients possessed the Cw*06 genotype.
Conclusions: Thus, not all patients with streptococcal-related psoriasis carry Cw*06. The role of Cw*06 in psoriasis, if any, has yet to be determined.