Genetic association between germline JAK2 polymorphisms and myeloproliferative neoplasms in Hong Kong Chinese population: a case-control study

The Contribution of JAK2 46/1 Haplotype in the Predisposition to Myeloproliferative Neoplasms

Haplotype 46/1 (GGCC) consists of a set of genetic variations distributed along chromosome 9p.24.1, which extend from the Janus Kinase 2 gene to Insulin like 4. Marked by four jointly inherited variants (rs3780367, rs10974944, rs12343867, and rs1159782), this haplotype has a strong association with the development of BCR-ABL1-negative myeloproliferative neoplasms (MPNs) because it precedes the acquisition of the JAK2V617F variant, a common genetic alteration in individuals with these hematological malignancies. It is also described as one of the factors that increases the risk of familial MPNs by more than five times, 46/1 is associated with events related to inflammatory dysregulation, splenomegaly, splanchnic vein thrombosis, Budd–Chiari syndrome, increases in RBC count, platelets, leukocytes, hematocrit, and hemoglobin, which are characteristic of MPNs, as well as other findings that are still being elucidated and which are of great interest for the etiopathological understanding of these hematological neoplasms. Considering these factors, the present review aims to describe the main findings and discussions involving the 46/1 haplotype, and highlights the molecular and immunological aspects and their relevance as a tool for clinical practice and investigation of familial cases.

JAK2 rs10974944 is associated with both V617F-positive and negative myeloproliferative neoplasms in a Vietnamese population: A potential genetic marker

The JAK2 gene encodes for a non‐receptor tyrosine kinase that plays a key role in the JAK/STAT signaling transfer pathway. Genetic polymorphisms of this gene have been indicated to be associated with myeloproliferative neoplasm‐associated thrombosis in recent studies. This research aimed to evaluate the association between the variant rs10974944 and different types of Myeloproliferative neoplasms disorders in the Vietnamese population. DNA samples were obtained from 172 essential thrombocythemia patients, 14 primary myelofibrosis patients, 76 polycythemia vera patients, and 192 healthy controls. The JAK2 rs10974944 and V617F genotypes were identified by the polymerase chain reaction‐restriction fragment length polymorphism genotyping and Sanger sequencing methods. Results showed that there was a strong association between rs10974944 and Myeloproliferative neoplasms phenotype (p < .0001) and the most significant association was observed in the recessive model of the mutant allele (G). The G allele carriers had a 1.74, 2.86, and 3.03 higher risk of getting essential thrombocythemia, primary myelofibrosis, and polycythemia vera, respectively. Interestingly, this effect of rs10974944 seemed to be independent of the JAK2 V617F genotype. The distribution of rs10974944 genotypes were significantly different between V617F‐positive and negative groups (p = .008). Moreover, the GG genotype of rs10974944 was observed to be associated with the risk of getting Myeloproliferative neoplasms both in JAK2 V617F‐positive group, and for the first time in JAK2 V617F‐negative patients. A systematic meta‐analysis in different populations strengthened the evidence regarding the correlation between rs10974944 and myeloproliferative neoplasm disorders. To sum up, our results suggested that rs10974944 can be used as a predisposition screening marker for predicting Myeloproliferative neoplasms susceptibility.

JAK2 Variant Signaling: Genetic, Hematologic and Immune Implication in Chronic Myeloproliferative Neoplasms

The JAK2V617F variant constitutes a genetic alteration of higher frequency in BCR/ABL1 negative chronic myeloproliferative neoplasms, which is caused by a substitution of a G ˃ T at position 1849 and results in the substitution of valine with phenylalanine at codon 617 of the polypeptide chain. Clinical, morphological and molecular genetic features define the diagnosis criteria of polycythemia vera, essential thrombocythemia and primary myelofibrosis. Currently, JAK2V617F is associated with clonal hematopoiesis, genomic instability, dysregulations in hemostasis and immune response. JAK2V617F clones induce an inflammatory immune response and lead to a process of immunothrombosis. Recent research has shown great interest in trying to understand the mechanisms associated with JAK2V617F signaling and activation of cellular and molecular responses that progressively contribute to the development of inflammatory and vascular conditions in association with chronic myeloproliferative neoplasms. Thus, the aim of this review is to describe the main genetic, hematological and immunological findings that are linked to JAK2 variant signaling in chronic myeloproliferative neoplasms.

Clonal Hematopoiesis: Somatic Mutations in Blood Cells and Atherosclerosis

The most important prognostic factor for atherosclerotic cardiovascular disease is age, independent of all other recognized risk factors. Recently, exome sequence analyses showed that somatic mutations in blood cells, a process termed clonal hematopoiesis, are common and increase in prevalence with age, with at least 1 in 10 adults older than 70 years affected. Carriers of clonal hematopoiesis have been shown to be not only at heightened risk for hematologic malignancy but also at increased risk for atherosclerotic cardiovascular disease. Here, we review the prior literature of clonal selection and expansion of hematopoietic stem cells and the evidence supporting its causal association with atherosclerotic cardiovascular disease.

Germline variations at JAK2, TERT, HBS1L-MYB and MECOM and the risk of myeloproliferative neoplasms in Taiwanese population

Germline variations at JAK2, TERT, HBS1L-MYB and MECOM have been found to associate with myeloproliferative neoplasms (MPNs) in European populations. Whether these germline variations are associated with MPNs in Taiwanese population is obscure. Here we aimed to evaluate the association of five germline variations (JAK2 46/1 haplotype tagged by rs12343867, JAK2 intron 8 rs12339666, TERT rs2736100, HBS1L-MYB rs9376092 and MECOM rs2201862) and the risk of MPNs in Taiwanese population. A total of 178 MPN patients (109 essential thrombocythemia, 54 polycythemia vera and 15 primary myelofibrosis) were enrolled into this study. The information of 17033 control subjects was obtained from Taiwan Biobank database. The JAK2 46/1 haplotype, JAK2 rs12339666 and TERT rs2736100 were significantly associated with Taiwanese MPNs (P = 3.6×10^-19, 1.9×10^-19 and 3.1×10^-6, respectively), and JAK2^V617F-positive MPNs (n=121) (P = 5.6×10^-21, 4.4×10^-21 and 8.6×10^-7, respectively). In JAK2^V617F-negative cases (n=55), only the JAK2 46/1 haplotype and JAK2 rs12339666 remained statistically significant (P= 0.009 and 0.007, respectively). When stratified by disease subtypes, the JAK2 46/1 haplotype and JAK2 rs12339666 were significantly associated with all three MPN subtypes, but TERT rs2736100 was only associated with essential thrombocythemia and polycythemia vera. We did not find any association of these five SNPs with CALR mutations in our cohort. Furthermore, the risk alleles of MECOM rs2201862 and HBS1L-MYB rs9376092 were demonstrated to be negatively associated with the risk of developing polycythemia vera. In conclusion, germline variations at JAK2 (both the 46/1 haplotype and rs12339666) and TERT rs2736100 were associated with MPNs in Taiwanese population.

Evaluating VEGFR1 genetic polymorphisms as a predisposition to AMD in a cohort from northern China

OBJECTIVE

The association among genetic variants in VEGFR1 and a predisposition to age-related macular degeneration (AMD) in a northern cohort from China was evaluated.

METHODS

A retrospective case-control correlation study was conducted on 432 cases and 906 gender-and ethnicity-matched controls. Whole DNA was isolated from peripheral blood samples after the individuals underwent detailed eye examinations. Eight single nucleotide polymorphisms (SNPs) in VEGFR1 genes were genotyped for all individuals using a MALDI-TOF technique. The distribution of genotypes was analyzed for Hardy-Weinberg equilibrium and the relationships among the genotype and allele frequencies with AMD were evaluated by age-adjusted logistic regression analysis. The measurement of linkage disequilibrium (LD) was carried out by Haploview 4.2. Bonferroni testing was employed to correct for multiple comparisons.

RESULTS

Among the SNPs genotyped, p values of six SNPs were less than 0.05 between AMD cases and unaffected controls. However, after Bonferroni correction, the genotype and allele distributions of only two SNPs, rs9554322 and rs9582036 differed significantly between the controls and AMD patients. Further, the rs9554322 CC genotype conferred strong susceptibility to AMD (OR = 6.057, 95% CI: 3.099-11.839). Rs9943922 was also found to be significantly associated with AMD in the distributions for the genotype and allele recessive model (p = 0.004). The specific haplotype CA of rs9582036 and rs9554320 was associated with AMD (p = 0.035), but the correlation did not remain after correction.

CONCLUSIONS

The SNPs rs9554322, rs9582036 and rs9943922 were correlated with AMD. Gene variants in VEGFR1 were linked to a pronounced emerging risk for AMD in a population in northern China.

Lentiginoses in polycythemia vera patient: Is there a role for JAK2 (V617F) mutation?

Lentiginoses is a clinical feature in which lentigines are remarkably present in large numbers or when they occur in a distinctive distribution on apparently normal skin. This entity may be congenital or acquired and may cover a wide spectrum of diseases ranging from an isolated benign pigmentary disorder to numerous syndromes associated with molecular abnormalities.We present a 59-year-old female patient with multiple lentigines which first emerged 3 y ago concurrently with policytemia vera. The patient had found to be positive for Janus Kinase-2 (JAK-2) mutation. Over activation of the pathway due to JAK-2 V617F mutation is a well-known condition in myeloproliferative diseases but has not been reported in melanocytic disorders. Moreover, several signaling pathways have previously been defined with lentiginosis except JAK-STAT pathway. We want to draw attention to the potential effect of JAK-2 mutation in lentigogenesis with this case report.