J Pediatr Genet 2023; 12(04): 308-311
DOI: 10.1055/s-0041-1728746
Case-Based Review

A De Novo Mosaic PHEX Variant Causing Sporadic X-Linked Hypophosphatemic Rickets in a 2-Year-Old Girl

1   Department of Laboratory Medicine, National University Hospital, Singapore
1   Department of Laboratory Medicine, National University Hospital, Singapore
Margaret Zacharin
2   Department of Hormone Research, Murdoch Children's Research Institute, Melbourne, Australia
3   Department of Paediatrics, University of Melbourne, Victoria, Australia
4   Department of Endocrinology & Diabetes, The Royal Children's Hospital, Melbourne, Victoria, Australia
5   Department of Paediatrics, Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore
6   Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
› Author Affiliations
Funding This study was supported by NUHS Allied Health and Nursing Grant 2014 (Ref: NUHSRO/2015/046/AHN/03) awarded to Kok-Siong Poon.


Pathogenic variants in the PHEX gene are causative of X-linked hypophosphatemic rickets (XLH). We present a case of a 2-year-old girl with hypophosphatemic rickets with genu varum and short stature without any family history of XLH. Next generation sequencing of the PHEX gene identified a splice donor variant, NM_000444.6:c.1173 + 5G > A in intron 10. This variant had a mosaic pattern with only 22% of the sequence reads showing the variant allele and was not present in the girl's parents, both of whom had a normal phenotype. This is a sporadic case of a de novo mosaic splice-site variant in the PHEX gene.

Publication History

Received: 08 January 2021

Accepted: 11 March 2021

Article published online:
01 June 2021

© 2021. Thieme. All rights reserved.

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