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The JAK2 46/1 haplotype predisposes to MPL-mutated myeloproliferative neoplasms.

ABSTRACT: The 46/1 JAK2 haplotype predisposes to V617F-positive myeloproliferative neoplasms, but the underlying mechanism is obscure. We analyzed essential thrombocythemia patients entered into the PT-1 studies and, as expected, found that 46/1 was overrepresented in V617F-positive cases (n = 404) versus controls (n = 1492, P = 3.9 x 10(-11)). The 46/1 haplotype was also overrepresented in cases without V617F (n = 347, P = .009), with an excess seen for both MPL exon 10 mutated and V617F, MPL exon 10 nonmutated cases. Analysis of further MPL-positive, V617F-negative cases confirmed an excess of 46/1 (n = 176, P = .002), but no association between MPL mutations and MPL haplotype was seen. An excess of 46/1 was also seen in JAK2 exon 12 mutated cases (n = 69, P = .002), and these mutations preferentially arose on the 46/1 chromosome (P = .029). No association between 46/1 and clinical or laboratory features was seen in the PT-1 cohort either with or without V617F. The excess of 46/1 in JAK2 exon 12 cases is compatible with both the "hypermutability" and "fertile ground" hypotheses, but the excess in MPL-mutated cases argues against the former. No difference in sequence, splicing, or expression of JAK2 was found on 46/1 compared with other haplotypes, suggesting that any functional difference of JAK2 on 46/1, if it exists, must be relatively subtle.

SUBMITTER: Jones AV

PROVIDER: S-EPMC3145114 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Myeloproliferative neoplasms constitute a group of diverse chronic myeloid malignancies that share pathogenic features such as acquired mutations in the JAK2, TET2, CBL and MPL genes. There are recent reports that a JAK2 gene haplotype (GGCC or 46/1) confers susceptibility to JAK2 mutation-positive myeloproliferative neoplasms. The aim of this study was to examine the role of the JAK2 GGCC haplotype and germline mutations of TET2, CBL and MPL in familial myeloproliferative neoplasms.We investigated patients with familial (n=88) or sporadic (n=684) myeloproliferative neoplasms, and a control population (n=203) from the same demographic area in Italy. Association analysis was performed using tagged single nucleotide polymorphisms (rs10974944 and rs12343867) of the JAK2 haplotype. Sequence analysis of TET2, CBL and MPL was conducted in the 88 patients with familial myeloproliferative neoplasms.Association analysis revealed no difference in haplotype frequency between familial and sporadic cases of myeloproliferative neoplasms (P=0.6529). No germline mutations in TET2, CBL or MPL that segregate with the disease phenotype were identified. As we observed variability in somatic mutations in the affected members of a pedigree with myeloproliferative neoplasms, we postulated that somatic mutagenesis is increased in familial myeloproliferative neoplasms. Accordingly, we compared the incidence of malignant disorders between sporadic and familial patients. Although the overall incidence of malignant disorders did not differ significantly between cases of familial and sporadic myeloproliferative neoplasms, malignancies were more frequent in patients with familial disease aged between 50 to 70 years (P=0.0198) than in patients in the same age range with sporadic myeloproliferative neoplasms.We conclude that the JAK2 GGCC haplotype and germline mutations of TET2, CBL or MPL do not explain familial clustering of myeloproliferative neoplasms. As we observed an increased frequency of malignant disorders in patients with familial myeloproliferative neoplasms, we hypothesize that the germline genetic lesions that underlie familial clustering of myeloproliferative neoplasms predispose to somatic mutagenesis that is not restricted to myeloid hematopoietic cells but cause an increase in overall carcinogenesis.

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The JAK2 46/1 haplotype predisposes to MPL-mutated myeloproliferative neoplasms.

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