The relationship between factor V Leiden, prothrombin G20210A, and MTHFR mutations and the first major thrombotic episode in polycythemia vera and essential thrombocythemia.

Arterial and venous thrombosis are the most frequent complications in patients with polycythemia vera and essential thrombocythemia. We sought to demonstrate a possible contribution of the factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) 677 C > T and 1298 A > C mutations to the thrombotic risk in patients with polycythemia vera and essential thrombocythemia along with other biological features of these patients. We included 86 patients with polycythemia vera, of which 34 (39.5 %) had major thrombosis and 95 patients with essential thrombocythemia, of which 22 (23.1 %) had major thrombosis. In the whole cohort of patients, only the factor V Leiden mutation was significantly associated with both arterial and venous thrombosis in univariate and multivariate analysis (odds ratio (OR) = 4.3; 95 % confidence interval (CI) = 1.5-12.5; p = 0.008 and OR = 4.3; 95 % CI = 1.2-15.9; p = 0.02, respectively). Other factors significantly associated with thrombosis in both univariate and multivariate analysis were male sex (OR = 2.8, 95 % CI = 1.4-5.4, p = 0.002 and OR = 3.5, 95 % CI = 1.6-7.6, p = 0.002, respectively) and the JAK2 V617F mutation (OR = 5.5, 95 % CI = 2.1-15, p = 0.0001 and OR = 6.9, 95 % CI = 2.2-21.2, p = 0.001, respectively). In conclusion, among the four mutations analyzed (factor V Leiden, prothrombin G20210A, and MTHFR 677 C > T and 1298 A > C), only factor V Leiden is a major contributor to thrombosis in polycythemia vera and essential thrombocythemia.

The G allele of the JAK2 rs10974944 SNP, part of JAK2 46/1 haplotype, is strongly associated with JAK2 V617F-positive myeloproliferative neoplasms.

Polycythemia vera, essential thrombocythemia, and primary myelofibrosis are myeloproliferative neoplasms, characterized in a majority of cases by a unique somatic point mutation, JAK2 V617F. Recently, it was shown that JAK2 V617F occurs more frequently on a specific JAK2 haplotype, named JAK2 46/1. We genotyped 149 myeloproliferative neoplasms patients (69 had polycythemia vera, 65 had essential thrombocythemia, and 15 had primary myelofibrosis) with a known JAK2 V617F mutational status and 150 controls for the JAK2 rs10974944 (C/G) single nucleotide polymorphism, in which the G allele tags the 46/1 haplotype. We found that the rs10974944 GG/CG genotypes were significantly enriched in patients compared to controls (p < 0.0001). After stratifying for the JAK2 V617F mutational status and for the mutant allele burden, we demonstrated that GG/CG genotypes were significantly more frequent in V617F positive compared to V617F negative patients (p = 0.001), but not in V617F negative patients compared to controls (p = 0.29). Similarly, the GG/CG genotypes were significantly enriched in V617F positive patients with a mutant allele burden >50% compared to those with a mutant allele burden <50% (p = 0.0006). Our results indicate that the G allele, part of the JAK2 46/1 haplotype, contributes significantly to the occurrence of JAK2 V617F-positive myeloproliferative neoplasms. Moreover, JAK2 46/1 seems to be associated with mutant allele burden >50% in JAK2 V617F-positive myeloproliferative neoplasms patients.

TET2 rs1548483 SNP Associating with Susceptibility to Molecularly Annotated Polycythemia Vera and Primary Myelofibrosis.

BACKGROUND: The complexity of myeloproliferative neoplasms (MPNs) cannot be characterized by acquired somatic mutations alone. Individual genetic background is thought to contribute to the development of MPNs. The aim of our study was to assess the association between the TET2 rs1548483 single nucleotide polymorphism (SNP) and the susceptibility to polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) or chronic myeloid leukemia (CML). METHODS: We evaluated the TET2 rs1548483 SNP through real-time PCR in 1601 MPN patients out of which 431 with PV, 688 with TE, 233 with PMF, 249 with CML and 197 controls. We included only patients with a molecularly proven driver mutation, such as JAK2 V617F, CALR or BCR-ABL1. RESULTS: Significant association between TET2 rs154843 variant allele and JAK2 V617F-positive PV and PMF (OR = 1.70; 95% CI: 1.01-2.91; p-value = 0.046, and OR = 2.04; 95% CI: 1.10-3.77; p-value = 0.024, respectively), and type 2 CALR-positive PMF (OR = 2.98; 95% CI: 1.12-7.93; p-value = 0.035) was noted. CONCLUSIONS: The TET2 rs1548483 SNP is associated with the susceptibility to molecularly annotated PV and PMF.

Among a panel of polymorphisms in genes related to oxidative stress, CAT-262 C>T, GPX1 Pro198Leu and GSTP1 Ile105Val influence the risk of developing BCR-ABL negative myeloproliferative neoplasms.

OBJECTIVES: To analyze the relationship between six polymorphisms in genes related to oxidative stress, namely CAT-262 C>T, MnSOD Ala16Val, GPX1 Pro198Leu, GSTM1 and GSTT1 null genotypes, and GSTP1 Ile105Val, and the occurrence of BCR-ABL negative myeloproliferative neoplasms (polycythemia vera, essential thrombocythemia, and primary myelofibrosis). METHODS: We genotyped for these polymorphisms 328 patients with a known mutation status for JAK2 V617F, MPL and CALR, and 363 controls, using molecular genetics assays. RESULTS: The CAT-262 C>T and GPX1 Pro198Leu polymorphisms were seen significantly less frequently, while the GSTP1 IleVal105 polymorphism was seen significantly more frequently in patients with BCR-ABL negative myeloproliferative neoplasms, regardless of the molecular sub-type (e.g. JAK2 V617F or CALR mutated). DISCUSSION AND CONCLUSION: Our study provides evidence that variation in genes related to oxidative stress might modulate the risk of developing BCR-ABL negative myeloproliferative neoplasms.

The XRCC1 Arg194Trp polymorphism is significantly associated with lung adenocarcinoma: a case-control study in an Eastern European Caucasian group.

DNA repair plays an important role in maintaining the integrity of the genome by repairing DNA damage induced by carcinogens. Certain genetic polymorphisms that occur in DNA-repair genes may affect the ability to repair DNA defects, and may represent a risk factor in carcinogenesis. The gene XRCC1 is involved in DNA repair. The purpose of our study was to investigate the association between XRCC1 Arg194Trp and Arg399Gln polymorphisms and the risk of lung cancer in a Romanian population. We recruited 222 healthy controls and 102 patients with lung cancer. Genotypes were determined by multiplex polymerase chain-reaction restriction fragment-length polymorphism. Statistical analysis (odds ratio, recessive model) revealed an increased risk for lung cancer for the homozygous 194Trp genotype (χ (2)=0.186, odds ratio 10.667, 95% confidence interval 1.309-86.933; P=0.007). Also, we found an association between the 194Trp allele and women with lung adenocarcinoma. In conclusion, the results of the study place the XRCC1 Arg194Trp polymorphism among independent risk factors for developing lung cancer.

Concomitant Myeloproliferative and Lymphoid Neoplasms in Two Patients Positive for JAK2 V617F Mutation. Case Report and Literature Review.

The coexistence of both myeloproliferative and lymphoproliferative neoplasms in the same patient is an uncommon finding. We report two patients who presented such an association. The first patient was initially diagnosed with essential thrombocythemia, developing a clinical and haematological picture consistent with chronic lymphocytic leukaemia several years afterwards. The second patient was diagnosed concomitantly with polycythaemia vera and chronic lymphocytic leukaemia. Both patients were positive for the JAK2 V617F mutation. In the first patient the chronic lymphocytic leukaemia was asymptomatic, stage A, and did not require any additional treatment, while the second patient presented with generalized large lymphadenopathy (stage B) and chronic lymphocytic leukaemia-related symptoms, requiring chronic lymphocytic leukaemia-directed treatment. It is unclear whether there is a pathogenetic link between the myeloproliferative and lymphoproliferative diseases encountered in these patients, both being probably the result of random mutations occurring in distinct initiating cells. However, given the higher risk of lymphoproliferative neoplasms development in myeloproliferative neoplasms patients reported in larger studies, the genomic instability characteristic to myeloproliferative neoplasms may play a role in subsequent lymphoproliferative neoplasms occurrence.

HFE gene C282Y, H63D and S65C mutations frequency in the Transylvania region, Romania.

BACKGROUND AND AIMS: HFE-associated haemochromatosis is one of the most frequent autosomal recessive disorders in the Caucasian population. Although most of the cases are homozygous individuals for the C282Y mutation, another two mutations, H63D and S65C, have been reported to be associated with milder forms of the disease. This study was a first attempt to evaluate the distribution of these HFE gene mutations in the Transylvania region. METHODS: Two-hundred and twenty-five healthy, unrelated volunteers originating from the Transylvania region, Romania, were screened for the HFE gene C282Y, H63D and S65C mutations, using molecular genetics assays (Polymerase Chain Reaction-Restriction Fragments Length Polymorphism). RESULTS: For the C282Y mutation, 7 heterozygotes (3.1%) were found, but no homozygous individual. In the case of the H63D mutation, 40 heterozygotes (17.8%) and 4 homozygotes (1.75%) for the mutant allele were evidenced. We found a compound heterozygous genotype (C282Y/H63D) in one individual (0.45%). Thus, the allele frequencies of the C282Y and H63D were 1.75% and 10.9%, respectively. Three individuals (1.3%) were found to harbour the S65C mutation in a heterozygous state, but none in a homozygous state: the allele frequency of the mutant allele was 0.75%. CONCLUSIONS: The distribution of the HFE gene C282Y, H63D and S65C mutations found in our group matches the tendencies observed in other European countries: a decreasing gradient from Northern to Southern Europe for the C282Y mutation; high frequency for the H63D mutation, and low frequency for the S65C mutation in most of the countries.

TLR1 polymorphisms in Europeans and spontaneous pregnancy loss.

Toll-like receptors (TLRs) are critical components of the pathogen recognition by the host innate immune system. Recently it has been shown that TLR1 is under evolutionary pressure in Europeans. This involves the positive selection of the nonsynonymous TLR1 1805G variant in Europeans, although this is associated with poor TLR1 response and unfavorable prognosis in various infections. In terms of natural selection, differential fertility is another mechanism, independent of infection susceptibility, that may explain the polymorphism pattern observed for TLR1. To test this hypothesis, we assessed the correlation of two TLR1 SNPs (T1805G and G239C) with spontaneous pregnancy loss in a case-control study that included 132 spontaneous pregnancy loss patients and 142 control volunteers. Similar allele frequencies of T1805G were observed between cases and controls, but GG genotype tended to be associated with pregnancy loss (OR 1.91; 95%CI 1.03, 3.53). No differences were observed for the TLR1 G239C SNP. Our findings showed slight differences in the distribution of T1805G variants in women with pregnancy loss, but these were not indicative of a protective effect of the TLR1 1805G allele for this fertility disorder. Although our hypothesis was not proven, potential effects of TLR1 polymorphisms on pregnancy outcome have been suggested, and future studies in larger cohorts are warranted.