Mutation of SGK3, a Novel Regulator of Renal Phosphate Transport, Causes Autosomal Dominant Hypophosphatemic Rickets.

Abstract

CONTEXT:

Hypophosphatemic rickets (HR) is a group of rare hereditary renal phosphate wasting disorders caused by mutations in PHEX, FGF23, DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3.

OBJECTIVE:

A large kindred with 5 HR patients was recruited with dominant inheritance. The study was undertaken to investigate underlying genetic defects in HR patients.

DESIGN:

Patients and their family members were initially analyzed for PHEX and FGF23 mutations using polymerase chain reaction sequencing and copy number analysis. Exome sequencing was subsequently performed to identify novel candidate genes.

RESULTS:

PHEX and FGF23 mutations were not detected in the patients. No copy number variation was observed in the genome using CytoScan HD array analysis. Mutations in DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3 were also not found by exome sequencing. A novel c.979-96 T>A mutation in the SGK3 gene was found to be strictly segregated in a heterozygous pattern in patients and was not present in normal family members. The mutation is located 1 bp downstream of a highly conserved adenosine branch point, resulted in exon 13 skipping and in-frame deletion of 29 amino acids, which is part of the protein kinase domain and contains a Thr-320 phosphorylation site that is required for its activation. Protein tertiary structure modelling showed significant structural change in the protein kinase domain following the deletion.

CONCLUSIONS:

The c.979-96 T>A splice mutation in the SGK3 gene causes exon 13 skipping and deletion of 29 amino acids in the protein kinase domain. The SGK3 mutation may cause autosomal dominant HR.

• Authors: Ayşe Nurcan Cebeci, Minjing Zou, Huda A BinEssa, Ali S Alzahrani, Roua A Al-Rijjal, Anwar F Al-Enezi, Futwan A Al-Mohanna, Etienne Cavalier, Brian F Meyer, Yufei Shi
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 105 Issue 6 (06 01 2020) ISSN: 1945-7197 [Electronic] United States
• PMID: 31821448 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © Endocrine Society 2019. All rights reserved. For permissions, please e-mail: [email protected].

Chemical References

• Biomarkers
• FGF23 protein, human
• Phosphates
• Fibroblast Growth Factor-23
• Protein Serine-Threonine Kinases
• SGK3 protein, human

Topics

• Adult
• Biomarkers (analysis)
• Child
• Child, Preschool
• DNA Mutational Analysis
• Familial Hypophosphatemic Rickets (etiology, metabolism, pathology)
• Female
• Fibroblast Growth Factor-23
• Humans
• Kidney (metabolism, pathology)
• Male
• Middle Aged
• Mutation
• Pedigree
• Phosphates (metabolism)
• Prognosis
• Protein Serine-Threonine Kinases (genetics)
• Rickets (etiology, metabolism, pathology)