PPAR-gamma gene polymorphisms and psoriatic arthritis.

OBJECTIVE

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activation has been shown to play a role in suppressing angiogenesis and inflammation, both important pathological features of psoriatic arthritis (PsA). Given the potential physiological role for PPAR-gamma in PsA, we examined known coding polymorphisms in the PPAR-gamma gene in a Caucasian population.

METHODS

PsA was diagnosed as an inflammatory arthritis in patients with psoriasis, in the absence of other etiologies for inflammatory arthritis. Control subjects were ascertained from the same population and were all Caucasian. DNA samples were genotyped for 4 PPAR-gamma variants by time-of-flight mass spectrometry using the Sequenom platform. All 4 single-nucleotide polymorphisms (SNP) were previously-reported coding variations, 3 of which caused an amino acid change: Pro12Ala (rs1801282), Pro40Ala (rs1805192), and Pro115Gln (rs1800571); the fourth SNP, C161T (rs3856806), was synonymous. All primers were designed using Sequenom SpectroDesigner software, and scanned using a mass spectrometry workstation.

RESULTS

Of the 4 SNP examined, Pro40Ala and Pro115Gln were found to be nonpolymorphic in our population. Minor allele frequency for patients with PsA and controls for Pro12Ala (G) were 9.0% vs 13.8% (p = 0.017) and for C161T (T) 10.7% vs 12.0% (p = 0.56), respectively. All genotypes satisfied Hardy-Weinberg equilibrium.

CONCLUSION

An association between PsA and a known coding SNP of the PPAR-gamma gene was observed in our Caucasian population. Further studies are now warranted for validation of our findings in an independent cohort.