This report describes chronic myeloid leukemia (CML). CML is most frequently caused by a cytogenetic abnormality known as the Philadelphia chromosome, where part of chromosome 22 translocates to chromosome 9. This creates a constitutively active fusion product of the human genes BCR and ABL1, both kinases.
Multiple groups have introduced a BCR-ABL1 fusion gene into flies (Hsap\ABL1::Hsap\BCR, Abl::Hsap\ABL1::Hsap\BCR). Expression of BCR-ABL1 in the eye produces undifferentiated, dysfunctional eyes, and lethality when expressed in the CNS. Expression in the lymph gland (the hematopoietic organ in Drosophila) causes hemocytes to aggregate and form melanotic nodules, a sign of excessive hematopoiesis. Use of the eye phenotypes has allowed screening of CML therapeutic drug candidates and regimens.
A mutation within the ABL1 kinase domain of the fusion protein is associated with resistance to tyrosine kinase inhibitors frequently used in treatment of CML. This mutation, ABL1:p.Thr315Ile , has been introduced into one of the BCR-ABL1 fusion constructs and has been characterized in flies, particularly in terms of mechanisms of drug resistance.
[updated Feb. 2020 by FlyBase; FBrf0222196]
[LEUKEMIA, CHRONIC MYELOID; CML](https://omim.org/entry/608232)
[ABL PROTOONCOGENE 1, NONRECEPTOR TYROSINE KINASE; ABL1](https://omim.org/entry/189980)
[BCR ACTIVATOR OF RhoGEF AND GTPase; BCR](https://omim.org/entry/151410)
Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of a pluripotent stem cell with a specific cytogenetic abnormality, the Philadelphia chromosome (Ph), involving myeloid, erythroid, megakaryocytic, B lymphoid, and sometimes T lymphoid cells, but not marrow fibroblasts. [from MIM:608232, 06.07.2019]
95% of CML patients have the translocation event which creates the constitutively active protein tyrosine kinase fusion gene BCR-ABL1. (Bernardoni et al. 2018 and references therein, FBrf0241911.)
Chronic myeloid leukemia is most frequently caused by a translocation between chromosomes 22 and 9, creating a BCR/ABL fusion gene encoding a tyrosine kinase. A distinct feature of disease progression is the appearance of additional cytogenetic abnormalities in the Ph-positive cells. This phenomenon, known as clonal evolution, frequently involves a second Ph, trisomy of chromosome 8, and isochromosome 17 and other abnormalities of chromosome 17 (Kantarjian et al., 1988, pubmed:3162181), although other abnormalities have been described. [from MIM:608232, 06.07.2019]
One to one: one human gene to one Drosophila gene.
One to one: one human gene to one Drosophila gene.
Single, moderate-ranking ortholog of human ABL1.
Single, high-ranking ortholog of human BCR.