The Manifestations and Complications of X-linked Hypophosphatemia in Saudi Arabia: A Retrospective Study

Background: X-linked hypophosphatemia (XLH) is a genetic disease of phosphate metabolism in which inactivating mutations of the phosphate regulating endopeptidase homolog, X-linked (PHEX) gene lead to local and systemic effects. In our pediatric clinics, XLH was observed to be associated with multiple complications despite conventional treatment. There is a need for novel treatment modalities to prevent disease progression and aid in the resolution of symptoms. Methods: This retrospective cross-sectional study aimed to understand the manifestations and complications of XLH in patients followed up at the endocrinology clinics in King Faisal Specialist Hospital and Research Center in Saudi Arabia. The study was conducted by reviewing the medical files of all XLH patients at the King Faisal Specialist Hospital and Research Center. Results: All the patients (N=24) who were included in this study had PHEX gene mutations. The mean age was 18.7 13.6 years and 68% were females. The mean height standard deviation score (HSDS) was ‑2.96 (-5.25 to -0.97) and 12 patients reached their final height (mean final HSDS, -3.28 [-1.39 to ‑5.39]). Skeletal deformities (mainly genu varum) were observed in 68% of the patients and 29% had craniosynostosis; 54% had undergone corrective osteotomy. Hyperparathyroidism was observed in 54% of the patients and 45% of the patients had nephrocalcinosis (grades 2/3). Conclusions: In our study, a majority of the XLH patients suffered from complications arising from the use of conventional therapy, thus indicating the need for novel treatment modalities for these patients. Additionally, no correlation between genotype and phenotype was found.