Genetic associations of psoriasis in a Pakistani population

Authors


  • Funding sources This work was supported by the U.S. National Institutes of Health (grants R01AR042742 and R01AR050511 to J.T.E.) and the Higher Education Commission of Pakistan (Higher Education Fellowship to P.A.S.). J.T.E. is supported by the Ann Arbor Veterans Affairs Hospital.
  • Conflicts of interest None declared.

Summary

Background

Genetic predisposition to psoriasis, an inflammatory skin disease affecting 0·2–4% of the world population, is well established. Thus far, 41 psoriasis susceptibility loci reach genome-wide significance ( 5 × 10−8). Identification of genetic susceptibility loci in diverse populations will help understand the underlying biology of psoriasis susceptibility.

Objectives

The primary objective of this study was to examine psoriasis susceptibility associations previously reported in Chinese and caucasian populations in a Pakistani cohort.

Methods

Blood samples and phenotype data were collected from psoriasis cases and controls in Islamabad, Pakistan. DNA was isolated and genotypes of selected susceptibility markers were determined. The data were analysed using χ2 tests or logistic regression for psoriasis association.

Results

HLA-Cw6 showed the strongest association [odds ratio (OR) 2·43, = 2·3 × 10−12]. HLA-Cw1 showed marginally significant association (OR 1·66, = 0·049), suggesting that the HLA-Cw1-B46 risk haplotype may be present in the Pakistani population. Three other loci (IL4/IL13, NOS2, TRAF3IP2) showed nominally significant association (< 0·05).

Conclusions

HLA-Cw6 is strongly associated with psoriasis susceptibility in the Pakistani population, as has been found in every other population studied. In addition, HLA-Cw1 showed marginal association, reflecting the relative geographical proximity and thus likely genetic relatedness to other populations in which the HLA-Cw1-B46 haplotype is known to be associated. A larger cohort and a denser marker set will be required for further analysis of psoriasis associations in the South Asian population.

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