ESPE Abstracts

X-linked dominant hypophosphatemic rickets (XLH) are the most common form of familial hypophosphatemic rickets resulting from hypophosphatemia caused by renal phosphate wasting, which in turn is a result of loss-of-function mutations in PHEX. Herein, we report a 39-year-old female with short stature and skeletal deformities and 12-month-old asymptomatic daughter. The woman has a history of multiple surgical treatments because of lower limb deformities. Through additional questions about the family, we found that her mother was also short stature. Her biochemical findings revealed low serum phosphorus levels with elevated serum alkaline phosphatase activity and normal serum calcium levels, suggesting presence of hypophosphatemic rickets. To identify the molecular causes, we used a multigene testing panel and found a mutation, c.667dup (P.Asp223GlyfsTer15), in PHEX gene. To the best of our knowledge, this is a novel mutation. A heterozygous form of the same variant was detected in her daughter. She presented no typical symptoms such as bow legs, frontal bossing, or waddling gate. But her biochemical findings suggested hypophosphatemic rickets like mothers and radiological findings showed early signs of impaired mineralization including widening, fraying, and cupping of the proximal tibial metaphysis and distal radial and ulnar metaphysis. The daughter was initiated onto early medical treatment with oral phosphate supplementation and an active vitamin D analog. Because the daughter was genetically diagnosed based on a family history before the onset of symptoms, appropriate medical management was possible from early infancy.