Patients included in the burosumab cohort had comparable baseline characteristics (age, race, and BMI) to patients in the pivotal phase 3 clinical trial of burosumab treatment in adults with XLH (NCT02526160); however, patients in the DMP exhibited higher mean baseline serum phosphate and 1,25(OH)2D and lower mean PTH concentrations, along with lower WOMAC (pain, stiffness, physical function) scores compared to the phase 3 clinical trial participants, indicating less severe disease.11 The gene discussed is PTH; the disease is X-linked hypophosphatemia.