PTPN22 and peeling skin syndrome: This study has important limitations as small sample size, selective recruiting of the western Mexican population, lack of inclusion of patients with the homozygous rs2488457 (−1123 CC) genotype for analysis of PTPN22 mRNA expression, lack of inclusion of control disease for comparative analysis of PTPN22 mRNA, as well as heterogeneity in the treatment of pSS, which may reflect differences in PTPN22 mRNA expression.