Thioredoxin Reductase 2 (TXNRD2) Mutation Associated With Familial Glucocorticoid Deficiency (FGD)
R Prasad, LF Chan, CR Hughes… - The Journal of …, 2014 - academic.oup.com
R Prasad, LF Chan, CR Hughes, JP Kaski, JC Kowalczyk, MO Savage, CJ Peters…
The Journal of Clinical Endocrinology & Metabolism, 2014•academic.oup.comContext: Classic ACTH resistance, due to disruption of ACTH signaling, accounts for the
majority of cases of familial glucocorticoid deficiency (FGD). Recently FGD cases caused by
mutations in the mitochondrial antioxidant, nicotinamide nucleotide transhydrogenase, have
highlighted the importance of redox regulation in steroidogenesis. Objective: We
hypothesized that other components of mitochondrial antioxidant systems would be good
candidates in the etiology of FGD. Design: Whole-exome sequencing was performed on …
majority of cases of familial glucocorticoid deficiency (FGD). Recently FGD cases caused by
mutations in the mitochondrial antioxidant, nicotinamide nucleotide transhydrogenase, have
highlighted the importance of redox regulation in steroidogenesis. Objective: We
hypothesized that other components of mitochondrial antioxidant systems would be good
candidates in the etiology of FGD. Design: Whole-exome sequencing was performed on …
Context
Classic ACTH resistance, due to disruption of ACTH signaling, accounts for the majority of cases of familial glucocorticoid deficiency (FGD). Recently FGD cases caused by mutations in the mitochondrial antioxidant, nicotinamide nucleotide transhydrogenase, have highlighted the importance of redox regulation in steroidogenesis.
Objective
We hypothesized that other components of mitochondrial antioxidant systems would be good candidates in the etiology of FGD.
Design
Whole-exome sequencing was performed on three related patients, and segregation of putative causal variants confirmed by Sanger sequencing of all family members. A TXNRD2-knockdown H295R cell line was created to investigate redox homeostasis.
Setting
The study was conducted on patients from three pediatric centers in the United Kingdom.
Patients
Seven individuals from a consanguineous Kashmiri kindred, six of whom presented with FGD between 0.1 and 10.8 years, participated in the study.
Interventions
There were no interventions.
Main Outcome Measure
Identification and functional interrogation of a novel homozygous mutation segregating with the disease trait were measured.
Results
A stop gain mutation, p.Y447X in TXNRD2, encoding the mitochondrial selenoprotein thioredoxin reductase 2 (TXNRD2) was identified and segregated with disease in this extended kindred. RT-PCR and Western blotting revealed complete absence of TXNRD2 in patients homozygous for the mutation. TXNRD2 deficiency leads to impaired redox homeostasis in a human adrenocortical cell line.
Conclusion
In contrast to the Txnrd2-knockout mouse model, in which embryonic lethality as a consequence of hematopoietic and cardiac defects is described, absence of TXNRD2 in humans leads to glucocorticoid deficiency. This is the first report of a homozygous mutation in any component of the thioredoxin antioxidant system leading to inherited disease in humans.
Oxford University Press