S100A2 coding sequence polymorphism: characterization and lack of association with psoriasis

Psoriasis is a chronic inflammatory skin disease with a strong genetic comp onent, Linkage studies have identified several susceptibility loci for psor iasis including a region on chromosome 1q21 termed the 'epidermal different iation complex'. At least 20 genes involved in epidermal differentiation an d proliferation have been mapped to this region including S100A2, a gene kn own to be over-expressed in psoriasis lesions. In the course of cloning and sequencing several S100A2 cDNAs, we identified an A/G (Asn62Ser) polymorph ism at nucleotide 185 of the S100A2 coding region. To determine whether thi s polymorphism is associated with psoriasis, we tested DNA from 38 unrelate d normal and 40 unrelated psoriatic individuals. The 185G allele was presen t in 148 of the 156 chromosomes analysed, giving an allele frequency of 94. 9%. All of the remaining chromosomes carried 185A. There was no significant difference in the allele distribution between normal and psoriatic individ uals (normals 72G, 4A; psoriatics 76G, 4A; P = 1.00 by Fisher's exact test) , Our data explain conflicting results in the literature regarding the sequ ence of S100A2 but provide no support for a direct causal role for S100A2 i n psoriasis.