Chronic Eosinophilic Leukaemia Associated with JAK2 Exon 13 Insertion/Deletion Mutations

How I diagnose and treat myeloid/lymphoid neoplasms with tyrosine kinase gene fusions

ABSTRACT

The fifth edition of the World Health Organization (WHO) classification and the International Consensus Classification (ICC) both include a category "myeloid/lymphoid neoplasms (MLN) with eosinophilia (eo) and tyrosine kinase (TK) gene fusions" (WHO, MLN-TK; ICC, M/LN-eo-TK). This rare group comprises phenotypically and prognostically heterogeneous disorders, which present a significant diagnostic challenge. The rapid and reliable identification of patients with MLN-TK may be delayed due to genetic complexity and significant phenotypic differences, including the chronic phase and primary/secondary blast phase (BP) of myeloid, lymphoid, or mixed phenotype in the bone marrow (BP-BM) and/or at extramedullary sites (extramedullary disease [EMD]). As a result, the entire armamentarium of conventional molecular genetic and cytogenetic techniques complemented by modern sequencing technologies, such as RNA sequencing or whole-genome sequencing, are often required to identify an underlying TK fusion. TK inhibitors (TKIs) with variable efficacy are available for all fusion genes, but a long-term favorable clinical course under TKI monotherapy is currently only observed in MLN-PDGFRA/PDGFRB fusion genes on imatinib. Because primary/secondary BP-BM/EMD occurs more frequently in MLN-FGFR1/JAK2/FLT3/ETV6::ABL1, a sequential combination of selective TKIs with or without prior intensive chemotherapy, rarely local radiotherapy, and/or subsequent allogeneic hematopoietic cell transplantation should be considered.

Relationship between Indel Variants within the JAK2 Gene and Growth Traits in Goats

Janus kinase 2 (JAK2) plays a critical role in myoblast proliferation and fat deposition in animals. Our previous RNA-Seq analyses identified a close association between the JAK2 gene and muscle development. To date, research delving into the relationship between the JAK2 gene and growth traits has been sparse. In this study, we sought to investigate the relationship between novel mutations within the JAK2 gene and goat growth traits. Herein, two novel InDel (Insertion/Deletion) polymorphisms within the JAK2 gene were detected in 548 goats, and only two genotypes were designated as ID (Insertion/Deletion) and DD (Deletion/Deletion). The results indicate that the two InDels, the del19008 locus in intron 2 and del72416 InDel in intron 6, showed significant associations with growth traits (p < 0.05). Compared to Nubian and Jianzhou Daer goats, the del72416 locus displayed a more pronounced effect in the Fuqing breed group. In the Nubian breed (NB) group, both InDels showed a marked influence on body height (BH). There were strong linkages observed for these two InDels between the Fuqing (FQ) and Jianzhou (JZ) populations. The DD-ID diplotype was associated with inferior growth traits in chest width (ChW) and cannon circumference (CaC) in the FQ goats compared to the other diplotypes. In the NB population, the DD-DD diplotype exhibited a marked negative impact on BH and HuWI (hucklebone width index), in contrast to the other diplotypes. In summary, our findings suggest that the two InDel polymorphisms within the JAK2 gene could serve as valuable molecular markers for enhancing goat growth traits in breeding programs.

Cytogenetics in the management of myeloproliferative neoplasms, mastocytosis and myelodysplastic/myeloproliferative neoplasms: Guidelines from the Group Francophone de Cytogénétique Hématologique (GFCH)

Myeloproliferative neoplasms, mastocytosis, myeloid/lymphoid neoplasms with hypereosinophilia and tyrosine kinase gene fusions, and myelodysplastic/myeloproliferative neoplasms are clonal hematopoietic cancers that, with the exception of certain entities, have an indolent course. In addition to their increasingly important role in the diagnosis of these entities, as shown by the recent classification of hematolymphoid tumors in the 5th edition of the World Health Organization and the International Consensus Classification of myeloid neoplasms and acute leukemias, identification of the profile of acquired genetic abnormalities is essential for adapting patient management and early detection of patients at high risk of progression. Alongside molecular abnormalities, cytogenetic abnormalities play an important role in the diagnosis, prognosis and follow-up of these diseases. Here, we review the recent literature on the impact of chromosomal abnormalities in these different entities and provide updated cytogenetic recommendations and guidelines for their management.