Background: Patients with nail psoriasis have an increased risk of onychomycosis. Previous studies suggest it may be due to structural changes of the nails. However, a genetic predisposition seems to be also at play.
Objective: To determine a genetic susceptibility for onychomycosis in nails with changes of psoriasis.
Methods: This is a prospective case-control study of patients with suggestive changes of nail psoriasis with onychomycosis (cases) and without onychomycosis (controls) confirmed by mycological tests. HLA typing was performed in all of them by sequence-specific primers.
Results: Twenty-five patients and 20 controls with a mean age of 50 years (range 37-72 years) were studied. HLA-DRB1*08 was found in 12 cases (48%) and only 3 controls (15%) [p < 0.033, odds ratio (OR) = 3.8, 95% confidence interval (CI): 0.9-19]. HLA-DR1 was found in 9 cases (36%) and only 1 control (5%) (p < 0.023, OR = 8.5, 95% CI: 1-188).
Conclusion: HLA-DR*08 and HLA-DR*01 probably increase the susceptibility to fungal infection in psoriasis-affected nails, but larger studies are required to confirm this observation.
Keywords: Genetic predisposition; HLA class II allele; Nail fungus; Nail psoriasis; Onychomycosis; Psoriasis.