cortodoxone and Hyperaldosteronism

Topics: Adrenal Cortex Diseases; Adrenal Hyperplasia, Congenital; Biomarkers; Cortodoxone; Cushing Syndrome; Humans; Hyperaldosteronism; Radioimmunoassay; Reference Values; Specimen Handling

We previously described an association between the -344C/T 5'-untranslated region (UTR) polymorphism in the CYP11B2 (aldosterone synthase) gene and hypertension with a raised aldosterone to renin ratio (ARR); the same genetic variant is also associated with impaired adrenal 11beta-hydroxylase efficiency. The -344 polymorphism does not seem to be functional, so is likely to be in linkage with variants in CYP11B1 that determine the associated variation in 11beta-hydroxylase efficiency. We therefore aimed to determine whether there is an association between CYP11B1 variants and hypertension and/or an altered ARR.. We screened 160 subjects divided into four groups, normotensive controls, unselected hypertensive subjects, and hypertensive subjects with either a high (> or = 750) or low ARR (< or = 200), for variants in the coding region of CYP11B1 by single-stranded conformation polymorphism (SSCP) and direct sequencing. The effects of these variants on enzyme function were assessed by conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone (DOC) to corticosterone.. Eight novel missense mutations were identified in the CYP11B1 gene that alter the encoded amino acids: R43Q, L83S, H125R, P135S, F139L, L158P, L186V and T196A. In each case they were heterozygous changes. However, no mutations were identified that could account for hypertension and/or a raised ARR. The variants L158P and L83S severely impaired enzyme function while R43Q, F139L, P135S and T196A enzymes resulted in product levels that were approximately 30-50% that of wild-type levels. The variant enzymes H125R and L186V resulted in substrate-specific alterations in enzyme function. H125R decreased conversion of 11-deoxycortisol to cortisol and L186V increased 11-deoxycortisol conversion. Neither had an effect on the conversion of DOC to corticosterone.. No variants were identified in the coding region of CYP11B1 that could account for hypertension and/or a raised ARR. However, this in vitro study identifies the importance of these affected residues to enzyme function and will inform subsequent studies of structure-function relationships.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aldosterone; Animals; Biological Assay; Case-Control Studies; Corticosterone; Cortodoxone; Desoxycorticosterone; Humans; Hydrocortisone; Hyperaldosteronism; Hypertension; Middle Aged; Mutation, Missense; Polymorphism, Single Nucleotide; Rats; Renin; Sequence Analysis, DNA; Steroid 11-beta-Hydroxylase

In glucocorticoid-remediable aldosteronism (GRA), there is a large interfamily variation of phenotype. We report three subjects with GRA in a single family (parents, two brothers and two sisters), of whom only one (proband) displayed classical features of the mineralocorticoid excess. The proband was a man found to be hypertensive and hypokalaemic at the age of 24 years. Plasma renin activity was suppressed and plasma aldosterone was repeatedly elevated. Blood pressure and aldosterone levels normalized within 5 days of dexamethasone therapy. The presence of a chimaeric CYP11B1/CYP11B2 gene was demonstrated by long-PCR and Southern blotting (crossover site at the end of intron 3) in the proband, in the younger sister (sibling 1) and in the father. In these patients, sequencing of the chimaeric portion of CYP11B1 did not reveal any mutation, while sequencing of the chimaeric portion of CYP11B2 showed a V386A polymorphism in exon 7, known to cause only a minimal impairment of enzymatic activity. Sibling 1 was normotensive, normokalaemic and had normal PRA and aldosterone. The father had normal blood pressure and potassium, low-normal PRA and normal aldosterone. All three subjects had elevated levels of urinary 18-hydroxycortisol and 18-oxocortisol. Baseline 11-deoxycorticosterone (DOC), corticosterone (B) and aldosterone were high in the proband and normal in the father and sibling 1; 11-deoxycortisol (S) and cortisol (F) were normal. ACTH induced a normal increase of B, DOC, S and F, and an excessive aldosterone increase in all three patients. Abnormalities in the chimaeric portions of CYB11B1 or CYP11B2 genes did not account for the phenotypic disparity of the different members in a single GRA family. Altered regulation of the chimaeric gene may be responsible for differences in its activity.

Topics: Adult; Aged; Aldosterone; Cortodoxone; Cytochrome P-450 CYP11B2; Dexamethasone; Female; Genotype; Glucocorticoids; Humans; Hydrocortisone; Hyperaldosteronism; Hypertension; Male; Middle Aged; Pedigree; Phenotype; Renin; Steroid 11-beta-Hydroxylase

CYP11B1 (11beta-hydroxylase) and CYP11B2 (aldosterone synthase) are 93% identical mitochondrial enzymes that both catalyze 11beta-hydroxylation of steroid hormones. CYP11B2 has the additional 18-hydroxylase and 18-oxidase activities required for conversion of 11-deoxycorticosterone to aldosterone. These two additional C18 conversions can be catalyzed by CYP11B1 if serine-288 and valine-320 are replaced by the corresponding CYP11B2 residues, glycine and alanine. Here we show that such a hybrid enzyme also catalyzes conversion of 11-deoxycortisol to cortisol, 18-hydroxycortisol, and 18-oxocortisol. These latter two steroids are present at elevated levels in individuals with glucocorticoid suppressible hyperaldosteronism (GSH) and some forms of primary aldosteronism. Their production by the recombinant CYP11B enzyme is enhanced by substitution of further amino acids encoded in exons 4, 5, and 6 of CYP11B2. A converted CYP11B1 gene, containing these exons from CYP11B2, would be regulated like CYP11B1, yet encode an enzyme with the activities of CYP11B2, thus causing GSH or essential hypertension. In a sample of 103 low renin hypertensive patients, 218 patients with primary aldosteronism, and 90 normotensive individuals, we found a high level of conversion of CYP11B genes and four cases of GSH caused by unequal crossing over but no gene conversions of the type expected to cause GSH.

Topics: Case-Control Studies; Catalysis; Cortodoxone; Cytochrome P-450 CYP11B2; Gene Conversion; Genetic Code; Genetic Testing; Humans; Hydrocortisone; Hyperaldosteronism; Hypertension; Renin; Steroid 11-beta-Hydroxylase

Corticosteroid 11 beta-hydroxylation is catalyzed by 11 beta-hydroxylase and aldosterone synthase. Using plasma steroid ratios, the level of this process in patients with glucocorticoid-suppressible hyperaldosteronism (GSH) was compared with that in unaffected control subjects and patients with Conn's syndrome. Based on both 11-deoxycortisol/cortisol (S:F) and 11-deoxycorticosterone/corticosterone (DOC:B) ratios, patients with GSH showed impaired resting 11 beta-hydroxylase activity. In GSH, but not in the other groups, the S:F ratio was significantly correlated with the basal plasma aldosterone concentration. ACTH infusion increased the S:F ratio in all of these patient groups, suggesting a common partial deficiency. The results also indicate that 11 beta-hydroxylation may be rate limiting in normal subjects. In control subjects and patients with Conn's syndrome, the DOC:B ratio was not affected by ACTH. However, in GSH patients, this ratio fell markedly, indicating an increased efficiency of 11 beta-hydroxylation of DOC (but not S). This may be due to the activation by ACTH of the zona fasciculata chimeric aldosterone synthase characteristic of this disease. Plasma aldosterone, corticosterone, and DOC concentrations appeared to be more sensitive to ACTH in GSH than in the other groups. The defect in 11 beta-hydroxylation in GSH accounts for the increased levels of DOC reported in this condition and may contribute to the phenotype variability.

Topics: Adrenal Cortex Neoplasms; Aldosterone; Corticosterone; Cortodoxone; Desoxycorticosterone; Glucocorticoids; Humans; Hydrocortisone; Hyperaldosteronism; Steroid 11-beta-Hydroxylase

Corticosteroid 11 beta-hydroxylation is catalysed by 11 beta-hydroxylase and aldosterone synthase. Using plasma steroid ratios, the level of this process in patients with glucocorticoid-suppressible hyperaldosteronism (GSH) was compared with that in unaffected control subjects and in patients with Conn's syndrome. Based on both 11-deoxycortisol:cortisol (S:F) and 11-deoxycorticosterone:corticosterone (DOC:B) ratios, patients with GSH showed impaired resting 11 beta-hydroxylase activity. In GSH, but not in the other groups, the S:F ratio was significantly correlated with basal plasma aldosterone concentration. ACTH infusion increased the S:F ratio in all these patient groups, suggesting a common partial deficiency. The results also indicate that 11 beta-hydroxylation may be rate-limiting in normal subjects. In control subjects and patients with Conn's syndrome, the DOC:B ratio was not affected by ACTH. However, in GSH patients, this ratio fell markedly, indicating an increased efficiency of 11 beta-hydroxylation of DOC (but not S). This may be due to the activation by ACTH of the zona fasciculata chimaeric aldosterone synthase characteristic of this disease. Plasma aldosterone, corticosterone and DOC concentrations, appeared to be more sensitive to ACTH in GSH than the other groups. The defect in 11 beta-hydroxylation in GSH accounts for the increased levels of DOC reported in the condition, and may contribute to the phenotypic variability.

Topics: Adrenocorticotropic Hormone; Aldosterone; Chimera; Corticosterone; Cortodoxone; Cytochrome P-450 CYP11B2; Desoxycorticosterone; Glucocorticoids; Humans; Hydrocortisone; Hyperaldosteronism; Hypertension; Steroid 11-beta-Hydroxylase; Zona Fasciculata

Patients with glucocorticoid-remediable aldosteronism (GRA) possess a chimeric gene resulting from fusion of the genes encoding steroid aldosterone synthase and 11 beta-hydroxylase. In the adrenal zona fasciculata, this may lead to ectopic expression under ACTH control of aldosterone synthase activity and increased formation of cortisol C18 oxidation products. We assessed mineralocorticoid and glucocorticoid pathways in three patients with GRA. Baseline plasma progesterone, 17 alpha-hydroxyprogesterone, corticosterone, and cortisol were normal in all patients, whereas 11-deoxycorticosterone, aldosterone, and 11-deoxycortisol were above normal. The ratios of both corticosterone/11-deoxycorticosterone and cortisol/11-deoxycortisol were abnormally low, and decreased further 60 min after administration of ACTH-(1-24) (250 micrograms) as an i.v. bolus. A low corticosterone/11-deoxycorticosterone ratio is consistent with an increased aldosterone synthase activity forming aldosterone by corticosterone. Similarly, a decreased cortisol/11-deoxycortisol ratio could reflect enhanced cortisol C18 oxidation. Our findings are in agreement with a hyperfunction of the 11 beta-hydroxylase/aldosterone synthase complex in the adrenal zona fasciculata of GRA induced by the new chimeric gene.

Topics: Adrenocorticotropic Hormone; Adult; Aldosterone; Cortodoxone; Cosyntropin; Desoxycorticosterone; Female; Glucocorticoids; Humans; Hydrocortisone; Hyperaldosteronism; Male; Reference Values

The in vitro metabolism of [1,2-3H] deoxycorticosterone (DOC), [1,2-3H] 18-hydroxy-11-deoxycorticosterone (18-OHDOC) and [1,2-3H] 11-deoxycortisol (S) was studied in adrenal adenoma homogenates from patients with primary hyperaldosteronism. Tumor tissues actively converted deoxycorticosterone and 18-hydroxy-11-deoxycorticosterone to 18-hydroxycorticosterone and aldosterone. Yields of cortisol and cortisone were also large showing that the tissues did not lack the zona fasciculata-like 11 beta-hydroxylation ability.

Topics: 18-Hydroxycorticosterone; 18-Hydroxydesoxycorticosterone; Adenoma; Adrenal Gland Neoplasms; Aldosterone; Cortisone; Cortodoxone; Desoxycorticosterone; Female; Glucocorticoids; Humans; Hydrocortisone; Hyperaldosteronism; Male; Mineralocorticoids

A 47-year-old female presented with hypertension, hypokalaemia, low plasma renin, high plasma aldosterone and was found to have a left adrenal tumour 4 cm in diameter by computerized tomography. Detailed biochemical studies showed high plasma levels of 11-deoxycorticosterone and corticosterone in addition to aldosterone and 18-hydroxycorticosterone. Basal 11-deoxycorticosterone levels were particularly high. Corticosterone, 18-hydroxycorticosterone and aldosterone concentrations were abnormally sensitive to infusions of ACTH and angiotensin II. Plasma cortisol and assays for sex hormones were normal although there was evidence that cortisol derived from the neoplasm. At operation a well-differentiated adrenocortical carcinoma weighing 50 g (56 X 30 X 36 mm) was removed. There was no evidence of metastases following surgery. Adrenal function returned to normal. Review of the literature suggests that adrenocortical carcinoma should be suspected in patients who otherwise have typical features of Conn's syndrome, but whose tumours are more than 3 cm in diameter. Measurement of steroids such as 11-deoxycorticosterone in addition to aldosterone is recommended since abnormally high values may also help to distinguish between hyperaldosteronism due to adenoma and carcinoma. Previously reported cases of isolated aldosterone production by a carcinoma cannot be substantiated.

Topics: 18-Hydroxycorticosterone; Adrenal Cortex Hormones; Adrenal Cortex Neoplasms; Adrenocortical Hyperfunction; Adrenocorticotropic Hormone; Angiotensin II; Corticosterone; Cortodoxone; Dexamethasone; Female; Humans; Hyperaldosteronism; Hypokalemia; Middle Aged