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Case Reports
. 2023;23(9):1235-1239.
doi: 10.2174/1871530323666230227142202.

A New de novo Mosaic Mutation of PHEX Gene: A Case Report of a Boy with Hypophosphatemic Rickets

Alessandra Terracciano  1 , Margherita Lucia De Bernardi  2 , Roberto Novizio  3 , Davide De Brasi  3 , Achille Iolascon  2 , Matteo Della Monica  4 , Francesco Scavuzzo  3 , Domenico Serino  3 , Antonio Novelli  1 , Carmelo Piscopo  4
Affiliations
Case Reports

A New de novo Mosaic Mutation of PHEX Gene: A Case Report of a Boy with Hypophosphatemic Rickets

Alessandra Terracciano et al. Endocr Metab Immune Disord Drug Targets. 2023.

Abstract

Background: X-linked hypophosphatemia is the most prevalent form of heritable rickets, characterized by an X-linked dominant inheritance pattern. The genetic basis of X-linked hypophosphatemia is a loss-of-function mutation in the PHEX gene (Phosphate regulating gene with Homology to Endopeptidases on the X chromosome), which leads to an enhanced production of phosphaturic hormone FGF23. X-linked hypophosphatemia causes rickets in children and osteomalacia in adults. Clinical manifestations are numerous and variable, including slowdown in growth, swing-through gait and progressive tibial bowing, related to skeletal and extraskeletal actions of FGF23. PHEX gene spans over 220 kb and consists of 22 exons. To date, hereditary and sporadic mutations are known (missense, nonsense, deletions and splice site mutations).

Case presentation: Herein, we describe a male patient carrying a novel de novo mosaic nonsense mutation c.2176G>T (p.Glu726Ter) located in exon 22 of PHEX gene.

Conclusion: We highlight this new mutation among possible causative of X-linked hypophosphatemia and suggest that mosaicism of PHEX mutations is not so uncommon and should be excluded in diagnostic workflow of heritable rickets both in male and female patients.

Keywords: FGF23; X-linked hypophosphatemia; dominant X-linked inheritance; endopeptidase; phosphate regulating gene; vitamin D resistant rickets.

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Conflict of interest statement

The authors declare no conflict of interest financial or otherwise.

Figures

Fig. (1)
Fig. (1)
Severe genu varum, tibial varism.
Fig. (2)
Fig. (2)
X-ray evaluation of the left leg.
Fig. (3)
Fig. (3)
X-ray evaluation of the right leg.
See this image and copyright information in PMC

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