In children with autoimmune thyroiditis CTLA4 and FCRL3 genes--but not PTPN22--are overexpressed when compared to adults.

BACKGROUND Numerous genetic studies revealed several susceptibility genes of autoimmune thyroid diseases (AITD), including CTLA4, PTPN22 and FCRL3. These immune-modulating genes are involved in genetic background of AITD among children and adult patients. However, possible age-related differences in overexpression of these genes remain unclear. PURPOSE The goal of this single centre cohort study was evaluation of expression levels of three (3) genes CTLA4, PTPN22 and FCRL3 in adult patients and children with autoimmune thyroiditis. METHODS A total of 47 patients--24 adults (mean age--47.7 years) and 23 children (mean age--12.4 years) with autoimmune thyroiditis were assessed for the level of expression of CTLA4, PTPN22 and FCRL3 genes, utilizing ABI PRISM' 7500 Sequence Detection System (Applied Biosystem, Foster City, CA, USA). RESULTS The overexpression of PTPN22 (mean RQ = 2.988) and FCRL3 (mean RQ = 2.544) genes were confirmed in adult patients with autoimmune thyroiditis, at the same time the expression level of CTLA4 gene was significantly decreased (mean RQ = 0.899) (p < 0.05). Similar discrepancies were not observed in children with autoimmune thyroiditis in whom overexpression of all three genes--CTLA4, PTPN22 and FCRL3--was observed. Differences in CTLA4 and FCRL3 genes expression levels in patients with autoimmune thyroiditis were found depending on the age, with increased expression levels of CTLA4 (mean RQ = 3.45 1) and FCRL3 (mean RQ = 7.410) in children when compared to adults (p < 0.05) (Mann-Whitney's U-test). There were moderate negative linear correlations between two genes in question (CTLA4 and FCRL3) expression level and patients' age [correlation coefficient (r) = -0.529 (p < 0.0002) and -0.423 (p < 0.0032), respectively; Spearman's rank correlation test]. CONCLUSION Our results are consistent with the hypothesis that there are few age-dependent genetic differences as regards autoimmune thyroiditis in adults and children. Accordingly, CTLA4 and FCRL3 genes overexpression may play an important role in children suffering from autoimmune thyroiditis.