Polymorphisms of B-lymphocyte-associated genes CD20 and FCRL5 are associated with susceptibility to autoimmune thyroid diseases.

Background: Recent studies have confirmed that B cell-related genes CD20 and FCRL5 may be involved in the pathogenesis of autoimmune thyroid diseases (AITDs). However, there is a lack of comprehensive genetic susceptibility studies on this subject.

Objective: The purpose of this study was to investigate the relationship of CD20 and FCRL5 gene polymorphisms with AITD susceptibility.

Methods: A total of 1740 subjects were recruited from the Chinese Han population. They consisted of 1007 patients with AITD and 633 healthy controls. Multiplex polymerase chain reaction (PCR) combined with high-throughput sequencing was used to genotype four screened single nucleotide polymorphisms (SNPs). The four SNPs were rs7126354 of CD20 and rs6667109, rs6692977 and rs3811035 of FCRL5.

Results: The minor allele frequency of rs7126354 was significantly lower in patients with AITD and Hashimoto's thyroiditis (HT) than in healthy controls (P = 0.031; P = 0.017). The minor allele frequency of rs6667109 was significantly higher in the Graves' disease (GD) subgroup than in the healthy control group (P = 0.029). In the Log-additive model, rs6667109 in the GD group also showed an increased risk of onset disease.

Conclusions: This study presents robust evidence of a genetic association of CD20 and FCRL5 with AITDs. The C allele of CD20 rs7126354 is a protective factor for HT susceptibility. The A allele of FCRL5 rs6667109 is a risk factor for the susceptibility to GD.