Fatigue and muscle weakness may seem routine, but when do they signal an underlying condition like thymidine kinase 2 deficiency (TK2d)? To find out, Dr. Alexandria May speaks with Dr. Kaitlin Batley, Director of the Pediatric Neuromuscular Program at Children’s Health and an Assistant Professor of Pediatrics and Neurology at UT Southwestern Medical Center. They discuss how multisystem involvement can help distinguish TK2d from more common neuromuscular disorders and how we can achieve diagnostic clarity through advanced genetic testing, metabolic evaluation, and muscle biopsy.