Association of cytotoxic T-lymphocyte antigen 4 gene with immune thrombocytopenia in Chinese Han children.

OBJECTIVES: To investigate the association of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) with immune thrombocytopenia (ITP).

METHODS: A case-control association analysis of 277 Chinese Han children was performed. The tagging variants rs11571315 and rs3087243 in the CTLA4 gene were detected using polymerase chain reaction-restriction fragment length polymorphism method. The expression quantitative trait loci (eQTL) analysis and quantitative real-time polymerase chain reaction were performed to determine the relationship of CTLA4 with ITP.

RESULTS: Neither SNP was significantly different between case and control groups in either the genotypic or allelic distribution. The eQTL analysis results indicated that in the spleen, the rs3087243 was significant with the expression of CTLA4. The rs11571315 has similar results. Interestingly, the transcript level of CTLA4 was found to significantly decrease in patients with ITP.

DISCUSSION: The autoimmune and gene etiology is implicated in the pathogen of ITP. The CTLA4 is important for negative regulation of T-cell activation, and CTLA-4 gene has been identified as a risk factor for some autoimmune diseases. However, association studies of ITP and CTLA4 gene have obtained conflicting results. This is the first study to systematically investigate the association of CTLA4 with ITP in Chinese Han children.

CONCLUSIONS: The CTLA4 gene is suggested to correlate with ITP through its abnormal expression level instead of gene site mutation.