We describe the case of a 6-year-old boy with both fragile X syndrome and Robertsonian Translocation (45, XY, der (13; 22) (q10; q10)). This is the first reported case of a patient with fragile X syndrome with this Robertsonian translocation. Facial features and macroorchidism were consistent with fragile X syndrome. Cognitive impairment is more significant than in his sibling with fragile X syndrome, and the patient also has a prior diagnosis of autism spectrum disorder. We emphasize the challenges in his behavioral management and outline future directions for his management.