The filaggrin null genotypes R501X and 2282del4 seem not to be associated with psoriasis: results from general population study and meta-analysis.

BACKGROUND

Psoriasis vulgaris could be associated with the filaggrin null genotype since certain known susceptibility loci for psoriasis are shared with susceptibility loci for atopic dermatitis. Furthermore, filaggrin expression is lowered in psoriatic skin lesions but normally expressed in uninvolved skin. So far five relatively small patient-based case-control studies have rejected a possible association between psoriasis and the two most prevalent filaggrin null mutations, 2282del4 and R501X.

OBJECTIVES

To reinvestigate a possible association between psoriasis and filaggrin null mutation status by using cross-sectional general population questionnaire data. Also, to perform a meta-analysis including published studies that investigated the relation between filaggrin gene mutations R501X and 2282del4, respectively, and psoriasis vulgaris.

METHODS

Between June 2006 and May 2008, a cross-sectional study was performed in the general population in Copenhagen. A random sample of 7931 subjects aged 18-69 years was invited to participate in a general health examination including a questionnaire and 3471 (43.7%) participated. A total of 3335 (96.1%) individuals were filaggrin genotyped for the 2282del4 and R501X mutations. A meta-analysis was undertaken to investigate the relation between filaggrin gene mutations and psoriasis vulgaris.

RESULTS

The prevalence of self-reported psoriasis was 6.7% among the 3240 respondents. The prevalence of the R501X and 2282del4 filaggrin null genotypes was 9.3% in subjects who reported psoriasis and 8.0% in subjects who did not report psoriasis (OR = 1.28; 95% CI = 0.74-1.89; P = 0.78). The meta-analysis found no association between the filaggrin null genotypes R501X and 2282del4 and psoriasis (OR = 1.04; 95% CI = 0.81-1.35).

CONCLUSIONS

Psoriasis was not associated with the R501X and 2282del4 filaggrin null genotypes in a general population study and in a meta-analysis on published studies.