RÉSUMÉ
Objective:To retrospectively analyze a pediatric case of X-linked hypophosphatemic rickets treated with Burosumab and improve clinicians′ awareness of the safety and effectiveness of the drug.Methods:Clinical data of the child were collected. Whole-exon genetic testing after parental consent confirmed X-linked hypophosphatemic rickets. During 18 months of Burosumab treatment, fasting blood phosphorus, alkaline phosphate, calcium, and calcium phosphate product were monitored every 11-14 days. Parathyroid hormone and 25 hydroxyvitamin D were checked every 2-6 weeks, while knee spacing, liver and kidney function, urinary calcium creatinine ratio, electrocardiogram were assessed every 3 months. Radiological imaging was performed every 6 months, with continuous follow-up of the child.Results:Whole-exon sequencing results showed a c. 1080_1081insCAATGTTA(p.T361Qfs*3) spontaneous heterozygous frameshift mutation in the PHEX gene in the child, which has not been reported previously. After the patient was treated with Burosumab for 18 months, the biochemical indexes were significantly improved, and the rickets score was reduced, without gingival abscess or other adverse events.Conclusion:The variant c. 1080_1081insCAATGTTA(p.T361Qfs*3) in the PHEX gene was identified as the cause of the patient′s condition. Burosumab, as a targeted therapeutic agent for X-linked hypophosphatemic rickets, showed significant treatment efficacy.