X-linked congenital adrenal hypoplasia: Report of long clinical follow-up and description of a new complex variant in the NR0B1 gene

Adrenal hypoplasia congenita, attributed to NR0B1 pathogenic variants, accounts for more than 50% of the incidence of primary adrenal insufficiency in children. Although more than 250 different deleterious variations have been described, no genotype-phenotype correlation has been defined to date. We report a case of an adopted boy who reported the onset of an adrenal crisis at 2 weeks of age, requiring replacement therapy with mineralocorticoids and glucocorticoids for 4 months. For 3 years, he did well without treatment. At almost 4 years of age, the disorder was restarted. A long follow-up showed the evolution of hypogonadotropic hypogonadism. Molecular studies on NR0B1 revealed a novel and deleterious deletion-insertion-inversion-deletion complex rearrangement sorted in the 5'-3' direction, which is described as follows: (1) deletion of the intergenic region (between TASL and NR0B1 genes) and 5' region, (2) insertion of a sequence containing 37 bp at the junction of the intergenic region of the TASL gene and a part of exon 1 of the NR0B1 gene, (3) inversion of a part of exon 1, (4) deletion of the final portion of exon 1 and exon 2 and beginning of the 3'UTR region, (5) maintenance of part of the intergenic sequence (between genes MAGEB1 and NR0B1, telomeric sense), (6) large posterior deletion, in the same sense. The path to molecular diagnosis was challenging and involved several molecular biology techniques. Evaluating the breakpoints in our patient, we assumed that it was a nonrecurrent rearrangement that had not yet been described. It may involve a repair mechanism known as nonhomologous end-joining (NHEJ), which joins two ends of DNA in an imprecise manner, generating an "information scar," represented herein by the 37 bp insertion. In addition, the local Xp21 chromosome architecture with sequences capable of modifying the DNA structure could impact the formation of complex rearrangements.

Neglected Adrenal Hypoplasia Congenita in Two Siblings with Novel Genetic Mutations in NR0B1 Gene and Notable Clinical Course: A Case Report

BACKGROUND

Adrenal Hypoplasia Congenita (AHC) is a rare subtype of primary adrenal insufficiency (PAI) that can go undiagnosed easily. In this article, we report two brothers with hypogonadotropic hypogonadism and novel mutations in the NR0B1 gene who were misdiagnosed and mismanaged as having congenital adrenal hypoplasia (CAH) for several years.

CASE PRESENTATION

Herein, we describe two brothers with similar histories; first, they were diagnosed with CAH and treated for that; however, after several years, they showed symptoms of lack of testosterone despite receiving CAH treatment. Low levels of testosterone and LH were detected in both, and a genetic test of CAH was negative for the first brother. Thereafter, DAX- 1 deficiency was suspected, and their genetic tests (the NR0B1 gene) confirmed the diagnosis of DAX-1.

CONCLUSION

The diagnosis of CAH in case of low levels of 17- OHP, testosterone, and LH, as well as central hypogonadotropic hypogonadism, should be studied, and further investigations are mandatory to evaluate other subtypes of PAI, especially AHC.

Adrenal Hypoplasia Congenita-Hypogonadotropic Hypogonadism Syndrome Due to NR0B1 Gene Mutations

Adrenal hypoplasia congenita (AHC) is a rare disorder of the adrenal gland due to mutations in the nuclear receptor superfamily 0, group B, member 1 (NR0B1) gene. It commonly presents with adrenal insufficiency and hypogonadotropic hypogonadism, but there is a wide variability in the age as well as the clinical phenotype at presentation. Also, the mechanism of pubertal abnormalities in this condition, which include not just delayed or absent pubertal development, but also precocious puberty in a small proportion of cases, is not clear. In this paper, three unrelated patients with 3 different mutations are described, who presented with variable age of onset of adrenal insufficiency, gonadal development, and puberty, highlighting the need for high index of suspicion of this condition in children presenting with atypical features of adrenal insufficiency.

Case Report: A Novel Truncating Variant of NR0B1 Presented With X-Linked Late-Onset Adrenal Hypoplasia Congenita With Hypogonadotropic Hypogonadism

Nuclear receptor subfamily 0 group B member 1 gene (NR0B1) encodes an orphan nuclear receptor that plays a critical role in the development and regulation of the adrenal gland and hypothalamic-pituitary-gonadal axis. In this study, we report a novel mutation in NR0B1 that led to adult-onset adrenal hypoplasia congenita (AHC) and pubertal development failure in a male adult. Clinical examinations revealed hyponatremia, elevated adrenocorticotropic hormone levels, reduced testosterone and gonadotropin levels, and hyper-responses to gonadotropin-releasing hormone and human chorionic gonadotropin stimulation tests. Whole-exome sequencing and Sanger sequencing were performed to identify the potential causes of AHC. Candidate variants were shortlisted based on the X-linked recessive models. Sequence analyses identified a novel hemizygous variant of c.1034delC in exon 1 of NR0B1 at Xp21.2, resulting in a frameshift mutation and premature stop codon formation. The c.1034delC/p.Pro345Argfs*27 in the NR0B1 gene was detected in the hemizygous state in affected males and in the heterozygous state in healthy female family carriers. These results expand the clinical features of AHC as well as the mutation profile of the causative gene NR0B1. Further studies are needed to elucidate the biological effects of the mutation on the development and function of the adrenal gland and the hypothalamic-pituitary-gonadal axis.

Case report: Clinical characteristics and treatment of secondary osteoporosis induced by X-linked congenital adrenal dysplasia

OBJECTIVE

To summarize the clinical features and bone complications in a patient from a large family with X-linked congenital adrenocortical hypoplasia (AHC) and evaluate the efficacy of different treatment regimens on the prognosis of secondary osteoporosis caused by AHC at a 5-year follow-up.

METHODS

A large family with AHC was recruited, and the causative gene mutation was identified by Sanger sequencing in the proband. Clinical features as well as radiological examinations and laboratory indices of osteoporosis secondary to AHC were analyzed in this study. Meanwhile, the proband was treated with classical antiresorptive drugs (bisphosphonates) for 2 years and switched to a vitamin K₂ analogue for another 3 years, during which the efficacy of the drugs was evaluated.

RESULTS

The proband was identified as carrying a homozygous insertion mutation (p. Thr193GlyfsX13) in the NR0B1 (nuclear receptor subfamily 0, group B, member 1) gene, resulting in a premature stop codon due to a frameshift mutation. During treatment and follow-up, the proband did not respond well to bisphosphonate and developed atypical femoral fractures. Vitamin K₂ improved clinical symptoms. In terms of bone mineral density (BMD), there is no evidence of any effect of vitamin K₂ on the neck of femur, though some minor effects on spinal BMD cannot be excluded.

CONCLUSIONS

Secondary osteoporosis induced by AHC deserves clinical attention. Unlike in primary osteoporosis, the curative effect of bisphosphonates was unsatisfactory and was more likely to cause atypical femoral fractures in long-term treatment. It is suggested that bone anabolic drugs may be better alternatives.

Testicular microlithiasis in a boy with X-linked adrenal hypoplasia congenita

X-linked adrenal hypoplasia congenita (AHC) is a rare disorder that usually presents clinically as adrenal insufficiency in early infancy. It is caused by mutations in the NR0B1 gene which is located on the short arm of chromosome X (Xp21). The NR0B1 gene plays an important role in normal development and function of both the adrenal and gonadal axes and some patients with the disease can present in adolescence with hypogonadotropic hypogonadism. Testicular microlithiasis is an ultrasonographic finding of unknown etiology that has been associated with several benign conditions such as cryptorchidism, congenital adrenal hyperplasia, varicoceles, and testicular malignancy. We report the case of an 11-year-old boy who was diagnosed at the age of 8 months with X-linked AHC due to adrenal failure and presented testicular microlithiasis during follow-up. To the best of our knowledge, this is the first case of an X-linked AHC patient diagnosed with testicular microlithiasis in follow-up.