A Novel PHEX Gene Mutation in a Patient with Sporadic Hypophosphatemic Rickets

Phosphate regulating gene with homologies to endopeptidases on the X-chromosome (PHEX) is a common cause of X-linked hypophosphatemic (XLH) rickets. Diverse PHEX gene mutations have been reported; however, gene mutations in sporadic rick-ets are less common than in XLH rickets. Herein, we describe a 50-year-old female patient with sporadic hypophosphatemic rick-ets harboring a novel splicing-site mutation in the PHEX gene (c.663+1G>A) at the exon 5-intron 5 boundary. The patient had recently suffered from right thigh pain and an aggravated waddling gait. She also presented with very short stature, generalized bone pain, and muscle weakness. Despite low serum phosphate levels, her phosphate reabsorption rate was lower than normal. Additionally, her 1,25-dihydroxyvitamin D3 concentration was lower than normal, although FGF23 level was normal. After treat-ment with alfacalcidol and elemental phosphate, her rachitic symptoms subsided, and callus formation was observed in the frac-ture site on the right femur