Acquired Ring Chromosomes in Tumors of Hematopoietic and Lymphoid Tissues

Acquired Ring Chromosomes (aRCs) are observed in various oncologic diseases. This chapter systematically curates the types of aRCs observed in different hematopoietic and lymphoid diseases and highlights the genomic content that contributes to hematopoietic and lymphoid diseases. The major hematologic malignancy entities covered here include Acute Myeloid Leukemia (AML), Myelodysplastic Syndromes (MDS), Chronic Myeloid Leukemia (CML), and other myeloid neoplasms. The major lymphoid tissue malignancy entities covered here include Acute Lymphoblastic Leukemias and lymphomas (ALL), Chronic Lymphocytic Leukemia (CLL), Plasma Cell Neoplasms (PCN), and other lymphoid neoplasms. The aRCs summarized here represent genomic imbalances and instability enabling growth, viability, or metabolic advantages via oncogenic amplification, novel gene fusions or copy number alterations, and other mechanisms to promote malignancy. Predisposition to AML and ALL from the constitutional RC21 is addressed. Compilation of these complex and rare cases of aRCs is needed to understand their contribution and ultimate impact in clinical diagnosis. This chapter presents conclusions and perspectives for affected patients bearing these aRCs in tumors of hematopoietic and lymphoid tissues. As cytogenomic technologies advance, future efforts should expand to identify underlying molecular mechanisms of forming aRCs and its pathogenesis effect on tumor initiation and progression for better clinical treatment and care management.