Session: FP10-Osteoporosis & Other Metabolic Bone Diseases
Bench to Bedside
Room 121 (Moscone Center)
Poster Board SAT-228
Examine the role of PHEX on bone and mineral metabolism by comparing the phenotype of patients with high FGF23 and HR due to PHEX or FGF23 mutations.
6 patients with FGF23 mutation and ADHR (4 children and 2 untreated adults); 23 patients with PHEX mutation and XLHR (18 children and 5 untreated adults); XLHR and ADHR patients were matched for age at start of treatment
Children with FGF23 mutations were diagnosed earlier (1.5±0.0 yrs) than children with PHEX mutations (2.3±0.2 yrs, p=0.03), with similar leg bowing (intercondylardistance 7.9±2.3 and 5.0±0 .7, respectively, p>0.05). At diagnosis, ADHR patients presented with bone demineralization (semi-quantitative assessment on X-rays) and fractures in one patient, whereas none of the 18 XLHR patients had bone demineralization or fractures. In addition, ADHR patients had significantly higher alkaline phosphatases than XLHR patients (2037±439 and 649±103, p=0.01, respectively). Phosphate, PTH and urinary calcium excretion were similar in both groups. Patients follow up revealed that, in opposition to XLHR, vitamin D analogs and phosphate supplements easily restored serum phosphate levels in ADHR; final height of untreated ADHR adults appears higher (-1.2 and -1 SD) than that of untreated XLHR (-3,2±1.3 SD).
Despite the limited number of patients, we pinpointed differences in the phenotypes of ADHR and XLHR. This suggests that the phenotype associated with PHEX deficiency does not uniquely result from FGF23 excess, yet advocates for a direct role of PHEX on bone mineralization and growth.
Nothing to Disclose: CT, LE, PFS, GR, EA, AR, GD, CC, DP, PK, CS, AL
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