Identification of a novel MEF2C::SS18L1 fusion in childhood acute B-lymphoblastic leukemia.

ABSTRACT

PURPOSE: Leukemia-associated fusion genes are closely related to the occurrence, development, diagnosis, and treatment of leukemia. DNA microarrays and second-generation sequencing have discovered multiple B-ALL fusion genes. We identified a novel MEF2CSS18L1 fusion gene in a child diagnosed with B-ALL. This study investigates the oncogenicity and prognosis of this fusion gene in B-ALL. METHODS: A child with B-ALL who has a MEF2CSS18L1 fusion is reported as a newly discovered case. Compared the breakpoints, structural domains, clinical phenotypes, and differential expression genes of MEF2CSS18L1 and MEF2DSS18.Using "ONCOFUSE" software, the carcinogenicity of MEF2CSS18L1 is predicted. Using whole transcriptome sequencing, we analyze the breakpoints and the secondary structure of the fusion protein. Further, we compared the structures, differentially expressed genes, and clinical phenotypes of MEF2D and MEF2C fusion genes by DESeq, GO functional enrichment, and flow cytometry immunophenotyping analysis. RESULTS: Whole transcriptome sequencing identified a MEF2CSS18L1 fusion transcript in a 3-year-old child with B-ALL. The MADS box, MEF structural domain, HJURP_C structural domain, and TAD I structural domain of MEF2C, and the QPGY structural domain of SS18L1, make up the fusion protein. "Oncofuse" found a 0.99 Bayesian probability that the fusion gene drives cancer. The breakpoint positions, fusion protein secondary structures, differentially expressed genes, and clinical characteristics of this patient were identical to those with MEF2DSS18 fusion gene. CONCLUSION: We identified a novel MEF2CSS18L1 fusion gene in childhood ALL, which shares similar structural and clinical characteristics with MEF2DSS18. Further studies with more samples should be conducted in future.