Alternative DNA structures in hematopoiesis and adaptive immunity.

Besides the canonical B-form, DNA also adopts alternative non-B form conformations which are highly conserved in all domains of life. While extensive research over decades has centered on the genomic functions of B-form DNA, understanding how non-B-form conformations influence functional genomic states remains a fundamental and open question. Recent studies have ascribed alternative DNA conformations such as G-quadruplexes and R-loops as important functional features in eukaryotic genomes. This review delves into the biological importance of alternative DNA structures, with a specific focus on hematopoiesis and adaptive immunity. We discuss the emerging roles of G-quadruplex and R-loop structures, the two most well-studied alternative DNA conformations, in the hematopoietic compartment and present evidence for their functional roles in normal cellular physiology and associated pathologies.

An Atypical Presentation of Hodgkin Lymphoma Invading the Myocardium.

Pericardial involvement by Hodgkin lymphoma has been found in up to 20% of children at presentation, but disease of the myocardium itself is rare. We describe an 18-year-old male with HL who presented with a large mediastinal mass, pericardial effusion, and tumor invasion of both atrial walls with intra-atrial extension. A PubMed search of publications between 1989 and 2022 was conducted and additional older references were identified among these publications. While pericardial disease is described in numerous case series, myocardial involvement by HL, diagnosed clinically rather than at autopsy, is distinctly unusual.