Quadruple the Considerations: Four Genetic Conditions Unveiled in the Setting of Developmental Delays Including a Complex DMD Rearrangement, Telomere Biology Disorder, and Neurodevelopmental Disorders.

This article focuses on a complex clinical case involving a 12-month-old male patient diagnosed with dystrophinopathy—an X-linked neuromuscular disorder caused by variants in the DMD gene—alongside three additional genetic conditions, including a telomere biology disorder and two neurodevelopmental disorders. The patient's atypical presentation, including global developmental delays and dysmorphic features, prompted extensive genetic testing that revealed a complex intragenic DMD inversion and multiple pathogenic variants, complicating diagnosis and management. The case underscores challenges in applying emerging genetically based therapies, such as adeno-associated virus (AAV)–mediated gene transfer, given potential risks related to coexisting genetic disorders like telomere biology disorder, which may increase susceptibility to liver disease and malignancy. The authors highlight the importance of advanced genetic testing technologies, such as optical genome mapping, for accurate variant characterization and emphasize the need for multidisciplinary care and cautious therapeutic decision-making in patients with multiple genetic diagnoses.