Bilateral Idiopathic Adrenal Hyperplasia: Genetics and Beyond.

Bilateral adrenal hyperplasia currently accounts for up to 2 thirds of cases of primary aldosteronism. As such, it represents a major opportunity for targeted medical management as opposed to unilateral surgically correctable forms of the disease. Although the majority of cases of primary aldosteronism are sporadic, bilateral adrenal hyperplasia may occur in the context of familial hyperaldosteronism where it is associated with specific germline mutations. Over the past 5 years, impressive progress has been made in our understanding of the genetic basis underlying primary aldosteronism, allowing us to identify and characterize new familial forms of the disease and to understand the mechanisms involved in the formation of aldosterone producing adenoma. In contrast, our knowledge of the genetic contribution to the development of bilateral adrenal hyperplasia, and in a larger context, to renin and aldosterone levels in the general population, is still poor. This review summarizes our current knowledge on the genetics of bilateral adrenal hyperplasia and addresses some open questions to be addressed by future research. In particular, genome-wide association studies in large populations may provide clues to understanding the genetic susceptibility underlying the development of primary aldosteronism.

[Virilizing congenital adrenogenital syndrome with a de novo I172N mutation: study of a new case]. / Síndrome suprarrenogenital congénito virilizante con mutación de novo I172N: estudio de un nuevo caso.

The classical form of congenital adrenal hyperplasia is the result of mutations in the 21-hydroxylase gene (CYP21A2). Most deficient alleles carry pre-existing mutations in the CYP21PA homologue pseudogene, located in tandem. Mutant alleles are inherited from carrier parents, and de novo mutations during gametogenesis or foetal development are exceptional. The present paper describes a de novo mutation occurring at the maternal allele (I172N) of a patient with a classical form of 21-hydroxylase deficiency, whose father was heterozygous for R356W. The mother did not carry the mutation. Microsatellite analyses confirmed a correct allelic segregation. The I172N mutation (in compound heterozygosity with a null mutation) gives rise to a virilizing phenotype not associated with salt-wasting.

[Polycystic ovary syndrome and congenital adrenal hyperplasia: a different entity for comparable phenotypes?]. / Syndrome des ovaires potykystiques et syndrome adrénogenital: une entité différente pour un phenotype comparable?

The phenotypes of the polycystic ovarian syndrome (PCOS) and congenital adrenal hyperplasia syndrome (CAHS) present a number of similarities. The main symptoms of PCOS are obesity, menstrual disorders, hirsutism, and low fertility in which the pituitary and adrenal glands are spared. The CAHS is a group of various entities all characterised by different degrees of malfunction of the 21-hydroxylase (CYP21) enzyme. The consequences are a downfall of the levels of aldosterone and cortisol, and the hyperproduction of adrenal androgen hormones. It is capital to be able to recognise these 2 entities in terms of identification of high risk families because the female foetuses suffering from CAHS will undergo severe virilization of there genitals in utero, which can efficiently be prevented by a administration of corticotherapy to the mother throughout the pregnancy.

[From gene to disease: adrenogenital syndrome and the CYP21A2 gene]. / Van gen naar ziekte; het adrenogenitaal syndroom en het CYP21A2-gen.

Congenital adrenal hyperplasia (CAH) is a disorder of adrenal steroid synthesis. In more than 90% of cases CAH is caused by CYP21 (21-hydroxylase) deficiency leading to impaired cortisol and aldosterone synthesis and an increase in ACTH secretion. This then leads to stimulation of the adrenal gland and overproduction of androgens with virilisation of female external genitalia. The CYP21 enzyme consists of 495 amino acids and is encoded by the CYP21A2 gene located on chromosome 6p21.3 close to a 98% homologous pseudogene (CYP21p). The pseudogene contains several inactivating mutations that may be transferred to the active CYP21A2 gene by gene conversion (more than 60% of the affected alleles) or gene deletion (30% of the affected alleles). The severity of the disease depends on the degree of CYP21 deficiency. The diagnosis can be made by measuring levels of 17-hydroxyprogesterone and androstenedione in serum.

[Molecular diagnostics in endocrine diseases]. / Molekylaerdiagnostikk av endokrine sykdommer.

Molecular diagnostic techniques provide an unsurpassed opportunity to understand the pathophysiological basis of endocrine disorders. Diseases have been associated with mutations in almost every gene known to have a role in either the production or secretion of a hormone or the mediators of hormone signalling. Even though most of these mutations are rare and account for only a small fraction of endocrine diseases, molecular diagnostics offers a valuable tool for the clinician in these cases. The most common endocrine disorders such as autoimmune thyroiditis, type 2 diabetes mellitus, osteoporosis, growth disorders, and obesity have all major genetic components, but these are mostly unknown. In this review the clinical implications of molecular diagnostics are illustrated for some endocrine diseases: congenital adrenal hyperplasia, congenital hypothyroidism, thyroid hormone resistance, familial hypocalciuric hypercalcaemia, growth hormone deficiency and resistance, and monogenic obesity. Improved diagnostic specificity has direct implications for treatment and follow up in these syndromes. Molecular diagnostics in endocrine tumours and diabetes are presented in two other articles in this series.