Leukemias diagnosed in <1-year-old infants generally have an aggressive clinical nature and unique biological characteristics. Acute lymphoblastic leukemia (ALL) in infants is still intractable and difficult to treat as compared with other pediatric ALLs, for which considerable progress in treatment outcomes has been recently achieved. Infant leukemia cells frequently carry chromosome translocations involving the 11q23 locus, resulting in the rearrangement and fusion of the KMT2A (MLL) gene. Among several KMT2A fusion genes, KMT2A-AFF1 (MLL-AF4) fusion is characteristically observed in neonatal and infant ALL, representing a hallmark of poor prognosis. The cytogenetic/molecular abnormalities t (1;22)(p13.3;q13.1)/RBM15-MKL1 and t (8;16)(p11.2;p13.3)/KAT6A-CREBBP (MOZ-CBP) are also well-known in acute myeloblastic leukemia in this population. Although many neonatal leukemias occurring within the first 28 days of birth are refractory, spontaneous remissions are occasionally observed, especially in the case of t (8;16). Therefore, international collaborative studies are necessary to improve understanding and facilitate the development of better treatment for this rare disease. Thus, this study summarizes the recently reported clinical, cytogenetic, and molecular biology aspects of neonatal and infant leukemias.
Keywords: Fusion gene; Infant; Leukemia; Neonate.