A novel presentation of familial glucocorticoid deficiency (FGD) and current literature review

Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disorder, which manifests as isolated glucocorticoid deficiency with normal mineralocorticoid function. The disease is secondary to ACTH unresponsiveness, with low serum cortisol concentrations in the presence of markedly elevated ACTH levels. Approximately 40% of patients with FGD have an identifiable mutation in the ACTH receptor gene. The typical presentation of FGD includes recurrent hypoglycemia, failure to thrive, and hyperpigmentation prior to 5 years of age. Patients with point mutations in the ACTH receptor gene are noted to be of tall stature. We report a patient with an atypical initial presentation of this condition. Our patient differed from the typical presentation by having late age of onset, short stature, and few symptoms of FGD. Sequence analysis of the ACTH receptor gene showed compound heterozygosity, with two previously reported mutations: S74I and T159K. Her unique presentation further illustrates the phenotypic heterogeneity of this disorder in light of reported mutations.