Prevalence of CYLD mutations in Vietnamese patients with polycythemia vera.

Background: Polycythemia vera (PV) is characterized by increased proliferation and accumulation of erythroid and mature myeloid cells and megakaryocyte in the bone marrow and peripheral blood. The JAK2V617F mutation is present in most PV patients. Deubiquitinase (DUB) genes, including TNFAIP3 (A20), CYLD and Cezanne, function as negative regulators of inflammatory reaction through nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ęB) signaling.

Objectives: To determine single nucleotide polymorphisms (SNPs) profiling and gene expression of the DUB genes as well as the immunophenotype of PV cells.

Material And Methods: Seventy-seven patients with PV and 55 healthy individuals with well-characterized clinical profiles were enrolled. Gene expression profile was determined using quantitative real-time polymerase chain reaction (qRT-PCR), the immunophenotype with flow cytometry, secretion of cytokines using enzyme-linked immunosorbent assay (ELISA), and gene polymorphisms using direct DNA sequencing.

Results: Inactivation of A20, CYLD and Cezanne, and increases in interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-á) levels, as well as the enhanced number of CD25+CD4 T, Th1 and regulatory T cells were observed in PV patients. The genetic analysis of the CYLD gene identified 11 SNPs, in which a novel W736G nsSNP in exon 15 and a SNP c.2483+6 T>G in intron 15 were observed in PV cases with the frequencies of 18.2% and 5.2%, respectively. The W736G non-synonymous SNP (nsSNP) was found to be most likely to exert deleterious effect and the intronic SNP c.2483+6 T>G was identified as aberrant splicing. Sequencing of Cezanne gene identified 7 SNPs in intron 10 and PV carriers of the SNPs had at least 2 SNPs in this gene. Importantly, PV carriers of the W736G nsSNP had multiple SNPs in CYLD, but not in A20 or Cezanne gene.

Conclusions: Two identified SNPs, including the W736G nsSNP and the SNP c.2483+6 T>G, in CYLD gene might be associated with a risk of PV disease, in which the deleterious effect of the W736G nsSNP in CYLD gene could contribute to the pathogenesis of PV.