B acute lymphoblastic leukemia

Immunophenotyping revealed that the leukemic blasts were positive for CD10, CD19, CD34, CD58, CD66c, CD38, CD79a, and HLA-DR.

Only one case to date: a 7-year-old boy (Sakamoto et al, 2016).

The patient achieved first complete remission under the extremely high-risk protocol (JACLS ALL-02), he underwent allogeneic HSCT due to a poor response to initial induction therapy. However, the patient relapsed and died in 5 years after the initial diagnosis (Sakamoto et al. ,2017).

PAX5/KIDINS220

Nucleotide sequence analyses revealed that PAX5 exon 7 was fused in-frame to KIDINS220 exon 20.

The PAX5 protein is fused in-frame to KIDINS220 at amino acids 306 and 871, respectively, resulting in the preservation of the N-terminal region of PAX5, including the DNA-binding domain, and the C-terminal region of KIDINS220, including several protein-protein interaction domains (Sakamoto et al., 2017). The PAX5/KIDINS220 fusion protein preserves the DNA-binding domain of PAX5 and growth promotion activities of KIDINS220.

The PAX5/KIDINS220 fusion protein plays a dual role in leukemogenesis: first, the fusion protein likely induces a block in the differentiation of B lymphocytes by inhibition of wild-type PAX5 function; second, it possibly enhances ERK signaling pathway activation through KIDINS220, resulting in increased proliferation and a survival advantage for leukemic cells. Functional studies need to be performed to determine the precise function of PAX5/KIDINS220 fusion (Sakamoto et al., 2017).

PAX5/KIDINS220