Association between polymorphism of CD20 gene and chronic lymphocytic leukemia in Chinese population.

Rituximab was widely used in clinical practice. Some chronic lymphocytic leukemia (CLL) patients were primary or secondary resistance to rituximab, but the mechanism has not been yet clear. CD20 gene coding region was amplified by PCR in 92 cases of newly diagnosed CLL patients and 200 healthy donors. The expression of CD20 was conducted in peripheral blood specimens of CLL patients. Proportions of CD20 expression and fluorescence intensity were detected by flow cytometry. Exon-3 c.246C>T (rs17155019) and Exon-4 c.632C>T (rs2070770) were present in 4.35% (4/92) and 9.78% (9/92) of newly diagnosed CLL patients. The mutations were not found in remaining exons. The frequency of C/C genotype and C allele of rs2070770 were significantly higher than the normal control population (90.22% vs 81.00%, P=0.04; 95.11% vs 90%, P=0.04). There was no significant relationship between genotypes with CLL development (P>0.05), however, C allele of rs2070770 may be associated with CLL (P=0.04, OR=0.46, 95% CI=0.22-0.98). The expression CD20 mRNA, proportion and intensity of CD20 were no significant different between genotypes of two polymorphic loci (P>0.05). Low expression of CD20 for CLL was not associated with mutation of CD20 gene coding region. Other mechanisms, such as promoter methylation, may result in low expression of CD20.