The aim of this study was to determine the association between polymorphisms in gene encoding B- and T-lymphocyte attenuator (BTLA) and susceptibility to chronic lymphocytic leukemia (CLL) and their influence on mRNA expression of BTLA gene in T and B cells from CLL patients (pts.). The following BTLA single-nucleotide polymorphisms (SNPs): rs2705511, rs1982809, rs9288952, rs76844316, rs16859633, rs9288953, rs2705535, rs1844089, rs2705565, rs2633580 were genotyped with use of TaqMan probes in 321 CLL pts. and in 470 controls. The mRNA levels of human BTLA were determined in subpopulations of T and B cells from 37 CLL patients with use of Applied Biosystems assays. Three SNPs: rs1982809, rs2705511 and rs9288953 were associated with susceptibility to CLL. The frequency of rs1982809[G] allele and rs2705511[C] allele carriers was higher in patients compared to the controls (0.51 vs. 0.41, OR 1.51, 95% CI 1.14-2.02, p = 0.004 and 0.56 vs. 0.44, OR 1.62, 95% CI 1.22-2.16, p = 0.0009, respectively). Furthermore, rs9288953[TT] genotype was overrepresented in CLL pts. compared to the controls (0.22 vs. 0.14, OR 1.74, 95% CI 1.20-2.53, p = 0.004). The evaluation of the influence of BTLA SNPs on BTLA mRNA expression in CLL pts. showed that the presence of rs1982809[G] allele was associated with lower median (±SD) BTLA mRNA expression in T cells (expressed as 2-delta Ct) in CLL pts. as compared to [AA] homozygotes (0.009 ± 0.013 vs. 0.026 ± 0.012, p = 0.03). Our results indicate that rs1982809 BTLA gene polymorphism is associated with mRNA expression level and that variations in the BTLA gene might be considered as potentially low-penetrating CLL risk factor.
Keywords: BTLA; Chronic lymphocytic leukemia; Gene polymorphisms; mRNA expression.