# Familial Glucocorticoid Deficiency Type 4 Caused by a Novel Mutation in the Nicotinamide Nucleotide Transhydrogenase (NNT) Gene: A Clinical Report of Two Siblings

## TL;DR

Two siblings with a rare adrenal disorder caused by a new mutation in the NNT gene showed improvement with hydrocortisone treatment.

## Contribution

A novel mutation in the NNT gene is reported as a cause of familial glucocorticoid deficiency type 4.

## Key findings

- The siblings exhibited hyperpigmentation and hypoglycemia, consistent with FGD type 4.
- Treatment with hydrocortisone led to significant clinical improvement in both patients.
- Genetic testing is emphasized for early diagnosis and management of FGD.

## Abstract

Familial glucocorticoid deficiency (FGD) is a rare genetic disorder characterized by impaired cortisol production, resulting in primary adrenal insufficiency. Clinical manifestations include hyperpigmentation, hypoglycemia, failure to thrive, and recurrent infections, often triggered by stress. FGD is commonly inherited in an autosomal recessive manner, with various genetic mutations contributing to its pathogenesis. This case report discusses two siblings diagnosed with FGD type 4 caused by a novel mutation in a gene associated with adrenal steroidogenesis. The siblings presented with symptoms such as hyperpigmentation and hypoglycemic episodes and were treated with hydrocortisone, leading to significant clinical improvement. This case highlights the importance of genetic testing for early diagnosis, enabling effective treatment and prevention of severe complications. Long-term follow-up and education remain vital for managing this condition.