Interleukin-10 promoter polymorphism in psoriasis

Beneficial effects of interleukin-10 therapy and lower endogenous interleuk in-10 formation compared with atopic dermatitis and cutaneous T cell lympho mas indicated that interleukin-10 is a key cytokine in psoriasis, The inter leukin-10 promoter is highly polymorphic, with two informative microsatelli tes, interleukin-10.G and interleukin-10.R. In order to understand whether interleukin-10 itself is a predisposing gene for the psoriasis susceptibili ty we analyzed interleukin-10 promotor polymorphism in patients. The distri bution of interleukin-10.G and interleukin10.R microsatellite alleles did n ot vary between patients (n = 78) and healthy controls (n = 80). In additio n, when the psoriasis patients were stratified according to age of onset (y ounger than 40 y of age, or age 40 and older), no difference in allele dist ribution was observed; however, a clear differential distribution was revea led at the interleukin10.G locus when patients were stratified according to whether they had a positive family history of psoriasis (p = 0.04). This d ifference was due to an over-representation of the interleukin10.G13 allele in those patients with familial disease (40.4% vs 19.6%, Chi-square = 7.29 2, p = 0.007). The positive association of allele interleukin10.G13 with fa milial psoriasis was especially true when patients with an early onset (< 4 0 y of age) of the disease were compared with those patients with early ons et against a nonfamilial background (39.6% vs 14.5%. Chisquare = 8.959, p = 0.003). Patients with age-of-onset of less than 40 were 4-fold [odds ratio = 3.85 (1.55-9.62)] more likely to have a psoriatic family background if t hey carried this interleukin10.G13 allele. These data suggest that the inte rleukin-10 locus contributes to the heritability of psoriasis susceptibilit y.