Rare PHEX intron variant causes complete and severe phenotype in a family with hypophosphatemic rickets: a case report.

Journal of pediatric endocrinology & metabolism : JPEM 2023 Jan 27

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Lower limb deformities in children need careful orthopedic evaluation to distinguish physiological forms from pathological ones. X-linked hypophosphatemia (XLH) is a rare hereditary condition caused by PHEX gene mutations where tibial varum can be the first sign. We report a family presenting with severe tibial varum, harbouring a rare PHEX intron mutation, c.1586+6T>C. This is the first clinical description available in literature for this variant. Despite the previous prediction of a mild phenotype in functional study, our patients showed important bone deformities, rickets and impaired growth since infancy followed by severe bone pain, hearing loss and reduced life quality in adulthood. Burosumab therapy improved biochemical and radiological findings in children and ameliorated quality of life in adults. This case demonstrated c.1586+6T>C causes a severe XLH phenotype, responsive to Burosumab. Familial genetic screening, enlarged to intronic region analysis, when XLH is suspected, allows precocious diagnosis to start timely the appropriate treatment. © 2022 Walter de Gruyter GmbH, Berlin/Boston.

Citation

Francesca Aiello, Daniela Pasquali, Federico Baronio, Alessandra Cassio, Cesare Rossi, Rosa Di Fraia, Raffaela Carotenuto, Lucia Digitale, Adalgisa Festa, Caterina Luongo, Giulio Maltoni, Roberta Schiano di Cola, Emanuele Miraglia Del Giudice, Anna Grandone. Rare PHEX intron variant causes complete and severe phenotype in a family with hypophosphatemic rickets: a case report. Journal of pediatric endocrinology & metabolism : JPEM. 2023 Jan 27;36(1):91-95