The Janus kinase (JAK) family is a small group of protein tyrosine kinases that represent a central component of intracellular signaling downstream from a myriad of cytokine receptors. The JAK3 family member performs a particularly important role in facilitating signal transduction for a key set of cytokine receptors that are essential for immune cell development and function. Mutations that impact JAK3 activity have been identified in a number of human diseases, including somatic gain-of-function (GOF) mutations associated with immune cell malignancies and germline loss-of-function (LOF) mutations associated with immunodeficiency. The structure, function and impacts of both GOF and LOF mutations of JAK3 are highly conserved, making animal models highly informative. This review details the biology of JAK3 and the impact of its perturbation in immune cell-related diseases, including relevant animal studies.

Colony-stimulating factor 3 (CSF3), additionally called granulocyte colony-stimulating factor (G-CSF), is the major cytokine regulating neutrophil production and also impacting their function. The actions of this cytokine are mediated through its unique receptor, the colony-stimulating factor 3 receptor (CSF3R). Several classes of pathogenic mutations in the CSF3R gene have been identified that have distinct biological properties and clinical impacts. This review provides an overview of CSF3R, the various pathogenic CSF3R mutations/variants and their biological effects. It also details the diseases to which they contribute, notably including chronic neutrophilic leukemia (CNL) and other myeloproliferative neoplasms (MPNs), myelodysplastic neoplasms (MDS), combined MDS/MPN disorders such as atypical chronic myeloid leukemia (aCML) and chronic myelomonocytic leukemia (CMML), as well as acute myeloid leukemia (AML) and lymphoid malignancies.

Acute myeloid leukemia (AML) is one of the most common types of hematological malignancies and a leading cause of cancer deaths. It is characterized by the rapid accumulation of typically immature myeloid cells that serve to disrupt the production of mature cells, leading to a range of clinical sequelae. The role of recurrent chromosomal aberrations has long been appreciated in this disease, but a myriad of gene mutations have been increasingly acknowledged as having important roles. This review provides a comprehensive overview of the mutational landscape of AML, discussing the various genetic lesions in terms of their function, classification, etiological role, prognostic value, therapeutic impact, detection, and monitoring, with a particular focus on gene mutations.