RESUMO
Congenital lipoid adrenal hyperplasia (lipoid CAH), the most severe form of CAH, is caused by mutations in the steroidogenic acute regulatory protein (StAR). Lipoid CAH is common among the Japanese, Korean, and Palestinian Arab populations, but is rare elsewhere. We describe six patients with lipoid CAH: four Japanese, one Palestinian, and one Guatemalan Native American. All had classical clinical presentations of normal female external genitalia in both genetic sexes, with severe glucocorticoid and mineralocorticoid deficiency presenting in the first month of life. Quite atypically, one patient had small adrenal glands shown by computed tomographic scanning. The StAR genes were characterized in all six patients. Three of the Japanese patients were compound heterozygotes for the common Japanese mutation Q258X in association with three different novel frameshift mutations; the fourth Japanese patient was homozygous for the mutation R182L, which is common among Palestinian patients but has not been described previously in a Japanese patient. Our Palestinian and Native American patients were each homozygous for novel frameshift mutations. Thus we have found five new frameshift mutations, but no new amino acid replacement (missense) mutations. This would be consistent with the view that only a small number of residues in the StAR protein are crucial for biological activity. The tomographic finding of small adrenals in a patient with genetically proven lipoid CAH due to a StAR mutation suggests a substantially broader spectrum of clinical findings in this disease than has been appreciated previously.
Assuntos
Hiperplasia Suprarrenal Congênita/genética , Mutação/genética , Fosfoproteínas/genética , Hiperplasia Suprarrenal Congênita/metabolismo , Adulto , Alelos , Aminoácidos/metabolismo , Árabes , Éxons/genética , Feminino , Guatemala , Humanos , Lactente , Japão , Cariotipagem , Metabolismo dos Lipídeos , Lipídeos/genética , Mutação/fisiologia , Fosfoproteínas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Low renin hypertension (LRH), which accounts for 10-20% of patients with idiopathic "essential" hypertension, bears hormonal similarities to mineralocorticoid-induced hypertension, but elevated mineralocorticoid concentrations have not been found. Some patients with LRH have normal, rather than suppressed, plasma aldosterone concentrations, so that the ratio of aldosterone concentration to PRA (Aldo/PRA) is high, suggesting inappropriately increased aldosterone biosynthesis. We characterized the CYP11B2 gene that encodes the aldosterone synthase, P450c11AS, in hypertensive and control populations in a single clinic in Santiago, Chile. We directly sequenced the entire CYP11B2 gene in 12 patients with LRH, 2 high renin hypertensive controls, and 2 normotensive controls. All sequences were identical, except that 8 of 24 LRH alleles encoded arginine rather than lysine at position 173. The Arg173 and Lys173 variants were expressed in transfected MA-10 cells, and their ability to convert deoxycorticosterone to aldosterone was measured; the apparent Michaelis constant (Km) for Lys173 was 2.73 mumol/L; the Km for Arg173 was 2.53 mumol/L. The apparent maximal velocity (Vmax) for Lys173 was 6.5 x 10(-3) micrograms/mL.24 h; the Vmax for Arg173 was 7.8 x 10(-3) micrograms/mL.24 h. The first order rate constant, Vmax/Km was 2.38 for Lys173 and 3.08 for Arg173. As these values were not significantly different, we sought to determine whether Arg173 is a polymorphism linked to LRH. We examined position 173 in 52 unselected patients with idiopathic hypertension and 55 normotensive controls by PCR amplification of CYP11B2 exons 3-5 followed by digestion with Bsu361, which digests the Arg173 sequence, but not the Lys173 sequence. More of the hypertensive alleles (39 of 104, 37.5%) than normotensive alleles (25 of 110, 22.5%) carried Arg173 (chi 2 = 5.57; P < 0.02). Most of the Arg173 alleles (31 of 72, 43.1%) were from hypertensive patients with Aldo/PRA below 30, whereas only 5 of 24 (20.8%) Arg173 alleles were found in patients with Aldo/PRA greater than 30 (chi 2 = 3.79; P = 0.05) Thus, the ARg173 variant of CYP11B2 may be linked to LRH in Chilean patients.
Assuntos
Citocromo P-450 CYP11B2/genética , Hipertensão/genética , Renina/sangue , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Reação em Cadeia da PolimeraseRESUMO
Mineralocorticoids are adrenal steroid hormones that regulate the retention of sodium by the kidney and, hence, are crucial in the regulation of sodium balance, intravascular volume, and blood pressure. The molecular biology of mineralocorticoid biosynthesis and action has only recently been elucidated. The genes encoding the various enzymes that convert cholesterol to mineralocorticoids have now been cloned. This has revealed the molecular basis of several inherited forms of mineralocorticoid excess, which cause hypertension, and several forms of mineralocorticoid deficiency, which cause salt loss. The cloning of the mineralocorticoid receptor revealed a paradox. Both the mineralocorticoid and the glucocorticoid receptor are activated equally by cortisol, even though cortisol has very modest mineralocorticoid activity. This is explained by the cloning of two genes for the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta HSD). Type-II 11 beta HSD, found primarily in the kidney, irreversibly converts cortisol to cortisone, which does not activate the mineralocorticoid receptor. Type-II 11 beta HSD thus defends the mineralocorticoid receptor from being activated by the very high concentrations of cortisol in the blood. Recent studies in genetically hypertensive rats suggest that other enzymes or factors that regulate salt balance may remain undiscovered. Thus the study of mineralocorticoid biosynthesis and action remains one of the most promising approaches to understanding hypertension.
Assuntos
Mineralocorticoides/genética , Mineralocorticoides/metabolismo , Animais , Humanos , Hipertensão/genética , Mineralocorticoides/biossíntese , Ratos , Receptores de Mineralocorticoides/química , Receptores de Mineralocorticoides/fisiologia , Síndrome de Emaciação/genéticaRESUMO
The relationship between diet diversity and hypertension was examined in a cross-sectional exploratory study of 82 randomly selected adult residents of Saba Island, Netherlands Antilles, in the eastern Caribbean Basin. Blood pressure measurements, taken over 4 years, and the appropriate use of antihypertensive medications, were used to identify chronic hypertensives. A 24-hour dietary recall, semi-quantitative food frequency interviews, and ethnographic confirmation techniques were used to calculate diet diversity, a measure of the overall dietary pattern. Results suggest hypertension is associated with lack of an overall balance of food groups in the daily diet beyond any imbalance of a particular dietary cation such as sodium, potassium, or calcium. Bivariate analyses found a significant association between a poorly diversified diet and hypertension (odds ratio [OR] = 4.25, 95 percent confidence intervals [CI] = 1.47,12.30). Dietary intake of sodium, potassium, and calcium was also examined and found not to be associated with the presence of hypertension in bivariate analyses. Including these cations individually in logistic regression models, which also included diet diversity, did not diminish the diet diversity-hypertension association. Multiple logistic regression models in which other potential confounding variables were individually entered as a control variable (body fat, skin color, age, sex, perceived stress, alcohol intake, aerobic activity, and socioeconomic status) did not alter this result. Analysis of the presence or absence of individual food groups indicate a lack of legumes in the daily diet is also associated with the diagnosis of hypertension (OR = 4.71, 95 percent CI = [1.71,13.01]).
Assuntos
Dieta , Hipertensão/etiologia , Adulto , Idoso , Intervalos de Confiança , Estudos Transversais , Registros de Dieta , Feminino , Humanos , Entrevistas como Assunto , Masculino , Pessoa de Meia-Idade , Antilhas Holandesas , Necessidades Nutricionais , Razão de Chances , Análise de Regressão , Fatores de Risco , Estudos de AmostragemRESUMO
Seven children and adolescents are described with mixed connective tissue disease. The patients had varying clinical features, commonly characterized by Raynaud phenomenon, arthritis, abnormal pulmonary function, and esophageal dysmotility. All patients had speckled antinuclear antibodies and high titers (greater than 1:100,000) of antibodies to ribonuclease-sensitive extractable nuclear antigen. We prepared extractable nuclear material from radioactively labeled HeLa cells, analogous to classic extractable nuclear antigen. Sera from all seven patients precipitated ribonucleoprotein containing the small nuclear ribonucleic acid species U1 from the HeLa cell extract. Antibody to U1 ribonucleoprotein was not found in sera from 51 of 53 children and adults having a variety of autoimmune and other diseases, nor in sera from nine normal individuals. The U1 ribonucleoprotein appears to be the component of extractable nuclear antigen characteristically reacting with sera from patients with mixed connective tissue disease. The finding of a distinct molecular marker in all children studied with mixed connective tissue disease indicates that this is a distinct disease entity and not a heterogeneous population of immune disorders.