No evidence for a role of the proximal IL-6 G/C -174 single nucleotide polymorphism in Italian patients with systemic sclerosis

In a recent issue of the JCMM, Sfrent-Cornateanu et al. [1] described an association between the G/A single nucleotide polymorphism (SNP) in the position -597 of the IL-6 gene, with disease activity and disability, but not with the disease per se, in 20 systemic sclerosis (SSc) patients.The idea of a disease-modifying, -rather than a disease-susceptibility, point mutation is intriguing and in line with others findings in the context of SSc [2–5]. Nonetheless, the inability to depict such an association could be attributable to the low number of subjects and indeed the possibility of a type II error in such a small group of patients is more than remote. Based on previous findings that indicate that the G/C substitution at position -174 -in complete linkage disequilibrium with the G/A-597 SNP-, is associated with an increased IL-6 production in vitro and in vivo [6], the authors anticipated a decreased risk for SSc in CC -174 (AA -597) individuals compared to GG -174 (GG -597) subjects and claimed further studies in larger patient groups to verify this hypothesis and their findings as well. The present retrospective case-control study was conducted on 196 consecutive patients with a diagnosis of SSc (ACR criteria [7]), referring to our outpatient clinic. One-hundred-ninety-six healthy sex-, ageand ethnically-matched subjects were included as controls. The number of patients and the case-to control ratio were chosen so as to obtain a power of No evidence for a role of the proximal IL-6 G/C -174 single nucleotide polymorphism in Italian patients with systemic sclerosis J. Cell. Mol. Med. Vol 11, No 4, 2007 pp. 896-899 Letter to the Editor