A case of infantile B-cell precursor acute lymphoblastic leukemia with NUTM1 fusion gene

Abstract

Infantile B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is generally associated with a poor prognosis, especially in the presence of KMT2A rearrangement or in early onset cases, with patients younger than 6 months at diagnosis. However, KMT2A-wildtype ALL is associated with better prognoses. In 2021, a worldwide study including Japan found nuclear protein in the testis member 1 (NUTM1) fusion gene-positive cases among KMT2A-wildtype infantile ALL, for which the 4-year overall survival rate was 100%.

We encountered a case of infantile BCP-ALL with NUTM1 fusion gene, diagnosed at 4 months. The patient was referred to our hospital for hepatosplenomegaly. She was diagnosed as having BCP-ALL. The initial bone marrow examination was negative for KMT2A gene rearrangement. Chromosome analysis revealed t(14;15)(q24;q15), which led to detection of the NUTM1 fusion gene. The presence of the NUTM1 fusion gene might be clinically important for infantile BCP-ALL with chromosome 15q abnormality.