Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We present an in vivo and in vitro study of congenital adrenal hyperplasia in a patient with 11beta-hydroxylase deficiency. Sequencing of the CYP11B1 gene showed two new base substitutions, a conservative 954 G-->C transversion at the last base of exon 5 (T318T), and a IVS8 + 4A-->G transition in intron 8. In addition, two polymorphisms were found in exons 1 and 2. The genetically female patient was raised as a male because of severe pseudohermaphroditism. Glucocorticoid-suppressive treatment encountered difficulties in equilibration and compliance, resulting in uncontrolled hypertension with pronounced hypertrophic cardiomyopathy. At 42 yr of age the occurrence of central retinal vein occlusion with permanent loss of left eye vision led to the decision to perform bilateral laparoscopic adrenalectomy. Surgery was followed by normalization of blood pressure and good compliance with glucocorticoid and androgen substitutive therapies. In vitro, adrenal cells in culture and isolated mitochondria showed extremely low 11beta-hydroxylase activity. Analysis of adrenal CYP11B1 messenger ribonucleic acid (mRNA) by RT-PCR and sequencing showed the expression of a shorter mRNA that lacked exon 8 and did not contain either the exon 5 mutation or the exon 1 and 2 polymorphisms. This suggested that one CYP11B1 allele carried the intron 8 mutation, responsible for skipping exon 8. The other allele carried the exon 5 mutation, and its mRNA was not detectable. Western blot analysis showed weak expression of a shorter CYP11B immunoreactive band of 43 kDa, consistent with truncation of exon 8. Thus, bilateral adrenalectomy in this patient allowed effective treatment of severe hypertension and helped in understanding the mechanisms and physiopathological consequences of two novel mutations of CYP11B1.
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PMID:Bilateral laparoscopic adrenalectomy for congenital adrenal hyperplasia with severe hypertension, resulting from two novel mutations in splice donor sites of CYP11B1. 1109 33

We present an in vivo and in vitro study of congenital adrenal hyperplasia in a patient with 11beta-hydroxylase deficiency. Genetic analysis showed two new base substitutions of CYP11B1, a conservative transition at the last base of exon 5, and a IVS8+4A-->G transition in intron 8. Difficulties with suppressive therapy resulted in severe hypertension. A laparoscopic adrenalectomy was decided which lead to normalization of blood pressure. In vitro, steroidogenesis by adrenal cells showed no measurable 11beta-hydroxylase activity. Analysis of CYP11B1 mRNA by RT-PCR and sequencing showed expression of a mRNA which lacked exon 8, presumably resulting from the intron 8 mutation. In addition a highly truncated mRNA was detected corresponding to exons 1, 2, 8, 9, with the loss of exons 3-7, presumably related to the exon 5 mutation. Western blot analysis showed a shorter CYP11B immunoreactive band of 43 kDa, consistent with truncation of exon 8. Thus adrenalectomy in this patient allowed effective treatment of severe hypertension and helped to understand the mechanisms of two novel mutations responsible for aberrant splicing of CYP11B1.
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PMID:Two novel mutations in splice donor sites of CYP11B1 in congenital adrenal hyperplasia due to 11beta-hydroxylase deficiency. 1119 57

In July 1998, Cortef oral suspension (Pharmacia & Upjohn) was reformulated changing the suspending agent tragacanth to xanthan gum. We subsequently observed suboptimal control of hormone levels in a group of children with classic congenital adrenal hyperplasia, despite increasing doses of Cortef suspension and stringent instructions to parents regarding shaking of the bottles of medication. Nineteen children receiving Cortef and fludrocortisone therapy were changed to hydrocortisone tablets and fludrocortisone, with a 10 percent reduction in hydrocortisone dose. A significant decrease in 17-hydroxyprogesterone (235 +/- 120 vs. 27 +/- 7 nmol/L; p</=0.001) and androstenedione (18.9 +/- 18.0 vs. 3.5 +/- 3.5 nmol/L; p=0.002) was observed 4-6 weeks later. Twenty-one percent (4/19) had 17-hydroxyprogesterone and androstenedione levels at or below the detection limit of the assay. Despite a significant reduction in glucocorticoid dose (19.6 +/- 4.7 vs. 17.6 +/- 3.9 mg/M(2)/day; p<0.001), eight children experienced significant weight gain and appetite increase, three experienced trouble sleeping, four experienced moodiness, and three developed hypertension requiring a decrease in fludrocortisone therapy. Hydrocortisone dose was further decreased to 15.2 +/- 2.6 mg/M(2)/day with resolution of symptoms. We conclude that Cortef suspension and hydrocortisone tablets are not bioequivalent and the reformulated form of hydrocortisone oral suspension was inadequate in the control of children with congenital adrenal hyperplasia. Cortef suspension has been recalled as a result of these data.
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PMID:Hydrocortisone suspension and hydrocortisone tablets are not bioequivalent in the treatment of children with congenital adrenal hyperplasia. 1123 38

Adrenocortical tumors are very rare in children. The records of seven patients (four boys and three girls) who attended Srinagarind Hospital between January 1986 and September 2000 were retrospectively reviewed. Virilization and hypertension were found in four patients, two of whom had untreated congenital adrenal hyperplasia. Hypertension or virilization was the single manifestation found in two other patients. Only one patient showed clinical symptoms of Cushing's syndrome and another nonfunctioning tumor in Down's syndrome. Abdominal ultrasonography was helpful in locating the tumors. Unilateral tumors were found in all of the patients and surgical exploration was done in six of them. Pathological examination revealed four adrenocortical carcinomas, one adrenal gland hyperplasia and one lipoma. The two patients in which the cancer metastasized to the liver and lungs died 1 and 1 1/2 months after diagnosis, respectively. The authors concluded that virilization and hypertension remain the primary diagnostic symptoms of adrenocortical tumors in children. Early detection and adrenalectomies prolonged the survival time in these patients.
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PMID:Adrenocortical tumors in children. 1133 77

Three disorders result from mutations involving two closely linked 11 beta-hydroxylase genes. Steroid 11 beta-hydroxylase deficiency results from mutations in CYP11B1. This is a form of congenital adrenal hyperplasia (CAH) characterized by hypertension and signs of androgen excess. Mutations in CYP11B2 cause aldosterone synthase deficiency, an isolated defect of aldosterone biosynthesis. Recombinations between these two genes cause glucocorticoid suppressible hyperaldosteronism, an autosomal dominant form of hypertension.
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PMID:Steroid 11 beta-hydroxylase deficiency and related disorders. 1134 39

The importance of hypertension in the pediatric population is not as well appreciated as in adults. This might be related in part to the lower prevalence of high blood pressure in this age group. As with height and weight, blood pressure increases with age during childhood. The underlying causes of significant hypertension in children differ considerably from those in adults: while the prevalence of hypertension in pediatrics is lower than in adults, clinically identifiable causes of hypertension are common. Abnormalities in steroid biosynthesis have been known for years to cause hypertension in some cases of congenital adrenal hyperplasia. In these patients, hypertension usually accompanies a characteristic phenotype with abnormal sexual differentiation. Recently, the molecular basis of four forms of severe hypertension transmitted on an autosomal basis has been elucidated: (a) the glucocorticoid-remediable aldosteronism (GRA), (b) the syndrome of apparent mineralocorticoid excess (AME), (c) activating mutation of the mineralocorticoid receptor and (d) Liddle's syndrome. All these conditions are characterized primarily by low or low-normal plasma renin, normal or low serum potassium and salt-sensitive hypertension, indicating an increased mineralocorticoid effect. These forms of juvenile hypertension are a consequence of abnormal biosynthesis, metabolism or action of steroid hormones: (a) GRA is due to expression of a chimeric gene produced by fusion of 11beta-hydroxylase aldosterone-synthase genes. Expression of the chimeric enzyme occurs in the zona fasciculata of the adrenal cortex under the control of ACTH and can be suppressed by administration of glucocorticoids. (b) AME is caused by mutations of the 11beta-hydroxysteroid dehydrogenase type 2 enzyme, an enzyme that metabolizes cortisol into its receptor inactive keto-form cortisone, thus protecting the mineralocorticoid receptor (MR) from occupation by glucocorticoids. (c) The activating mutation of the MR results in constitutive MR activity and alters receptor specificity, with progesterone and other steroids lacking 21-hydroxyl groups becoming potent agonists. (d) Liddle's syndrome is due to mutations in the beta or gamma chain of the epithelial sodium channel in distal renal tubule cells. The hyperactivity of this channel caused by the mutations results in increased sodium reabsorption. With the advent of molecular biology in clinical practice it has become evident that some genetic defect may present with a more discrete phenotype, with only moderate hypertension with or without hypokalemia as presenting feature. Considering that hypertension in children and adolescents is often 'nonessential', a search for disorders should be integral part of the diagnostic work-up in young patients with hypertension.
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PMID:Juvenile hypertension, the role of genetically altered steroid metabolism. 1174 Jan 42

Abnormalities in steroid biosynthesis have been known for years to cause hypertension in some cases of congenital adrenal hyperplasia. In these patients hypertension usually accompanies a characteristic phenotype with abnormal sexual differentiation. Recently, the molecular basis of four forms of severe hypertension transmitted on an autosomal basis but without additional phenotypic features has been elucidated. All these conditions are characterized primarily by low plasma renin, normal or low serum potassium, and salt-sensitive hypertension, indicating an increased mineralocorticoid effect. These four disorders, the glucocorticoid remediable aldosteronism, the syndrome of apparent mineralocorticoid excess, the activating mutation of the mineralocorticoid receptor, and the Liddle syndrome are a consequence of either abnormal biosynthesis, metabolism, or action of steroid hormones, and are ultimately characterized by an overactivation of the epithelial sodium channel in distal renal tubules. Hyperactivity of this channel results in increased sodium reabsorption and volume expansion leading to an increase in blood pressure as well as potassium loss. With the advent of molecular biology in clinical practice, it has become evident that some genetic defect may present with a more discrete phenotype, with only moderate hypertension with or without hypokalemia as the sole feature. A search for genetic disorders of the mineralocorticoid axis should be an integral part of the diagnostic work-up, particularly in young adults with hypertension.
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PMID:Genetics of the mineralocorticoid system in primary hypertension. 1179 Feb 87

Seventeen alpha-hydroxylase/17,20-lyase deficiency is a rare, autosomal recessive form of congenital adrenal hyperplasia not linked to human leukocyte antigen and characterized by the coexistence of hypertension caused by the hyperproduction of mineralocorticoid precursors and sexual abnormalities, such as male pseudohermaphroditism and sexual infantilism in female, due to impaired production of sex hormones. Both 17alpha-hydroxylase and 17,20-lyase reactions are catalyzed by a single polypeptide, cytochrome P450c17 (CYP17), which is encoded by the CYP17 gene located on chromosome 10q24-q25. Mutations in the CYP17 gene have been recognized to cause the 17alpha-hydroxylase/17,20-lyase deficiency syndrome. Here, we describe two phenotypically and hormonally affected Italian patients with 17alpha-hydroxylase/17,20-lyase deficiency. The family history revealed consanguinity of the parents. Linkage and haplotype analyses using microsatellites on chromosome 10q24-q25 demonstrated that the two affected individuals were homozygous at these loci. The mutation screening of the CYP17 gene identified a new Phe93Cys missense mutation in exon 1. The amino acid substitution is located in a highly conserved region of the protein and is not a polymorphism because it is not present in one hundred normal alleles. In vitro functional studies showed that the Phe93Cys mutated CYP17 retains only 10% of both 17alphahydroxylase and 17,20-lyase activities, according to the severe phenotype. Our results shed more light on the structure-function relationship of the CYP17 protein indicating that Phe 93 is crucial for both enzymatic activities.
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PMID:Combined 17alpha-Hydroxylase/17,20-lyase deficiency caused by Phe93Cys mutation in the CYP17 gene. 1183 39

Prenatal diagnosis of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is possible using chorionic villus and amniotic fluid cells for DNA analysis of the CYP21B gene and the C4 and HLA class I and II genes. Mutations can be identified on 95% of the chromosomes using Southern blot analysis and selective amplification of the CYP21B gene by polymerase chain reaction followed by allele-specific hybridization with oligonucleotide probes for a panel of nine known CYP21B mutations. Prenatal treatment with dexamethasone at doses between 0.5 and 2 mg/day is successful in three-quarters of the treated cases in eliminating or reducing the masculinization of the affected female external genitalia. The mother must be closely monitored for any adverse effects to her health such as hypertension or glucose intolerance. Prenatal dexamethasone treatment does not seem to have an adverse effect on growth, psychological development, or school performance except for increased shyness, internalizing and decreased social behavior. Animal studies, however, have shown abnormalities in the fetal brain and behavior of the animals. Prenatal dexamethasone treatment is still offered with caution to the parents of a potentially affected CAH female.
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PMID:Prenatal diagnosis and treatment of congenital adrenal hyperplasia and consequences in adults. 1196 26

Data related to genetics of congenital adrenal hyperplasia with emphasis on CYP21 gene defects are briefly outlined. Mutations of the StAR gene lead to impaired translocation of cholesterol from the outer mitochondrial membrane to the inner mitochondria, a rate limiting step in steroidogenesis in the adrenals and the gonads. The clinical picture is characterized by adrenal and gonadal insufficiency and sex reversal in XY individuals. Molecular defects of the CYP17 gene encoding 17alpha-hydroxylase can cause hypertension, impaired sexual maturation and impaired sexual differentiation in XY individuals. Molecular defects of the CYP11B1 gene lead to 11-hydroxylase deficiency, which is clinically expressed with virilization of the external genitalia of the female and precocious puberty in the male, as well as hypertension in both sexes. The HSD3beta1 and HSD3beta2 genes encode two isoenzymes (3betaHSDI and 3betaHSDII). The clinical picture results from either absence or diminished activity of type II 3betaHSD, resulting from mutations of the HSD3beta2 gene. The most frequent form of CAH (90% of all patients) is due to deletions, conversions or point mutations of the CYP21 gene, which encodes the enzyme 21-hydroxylase. There is a wide range of clinical expression primarily explained by the type of the molecular defect. The ratio of genotype to phenotype concordance varies in the different forms of the disease, the highest one being encountered in the non-classical form. Heterozygosity of CYP21 mutations may be expressed as premature pubarche.
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PMID:Genetic aspects of congenital adrenal hyperplasia. 1196 27


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