Psoriasis is a multifactorial hereditary skin disease. The searches for causative DNA variations have generated several susceptibility loci, but at present, the gene(s) involved has not been identified. In this article, we investigated whether cystatin A, an upregulated gene in psoriatic plaques and located at chromosome 3q21, is the disease-causing gene at the psoriasis susceptibility locus PSORS5. We also investigated association to a second gene located in this region, zinc finger protein 148. The two genes have been sequenced in a small case/control set in search for SNP markers, followed by family-based association analysis using the transmission disequilibrium test. We did not detect association with either of the genes.