Steroid biomarkers for identifying non-classic adrenal hyperplasia due to 21-hydroxylase deficiency in a population of PCOS with suspicious levels of 17OH-progesterone.

OBJECTIVE: We aimed at defining the most effective routine immunoassay- or liquid chromatography-tandem mass spectrometry (LC-MS/MS)-determined steroid biomarkers for identifying non-classic adrenal hyperplasia due to 21-hydroxylase deficiency (21-NCAH) in a PCOS-like population before genotyping. METHODS: Seventy PCOS-like patients in reproductive age with immunoassay-determined follicular 17OH-progesterone (17OHP) ≥ 2.00 ng/mL underwent CYP21A2 gene analysis and 1-24ACTH test. Serum steroids were measured by immunoassays at baseline and 60 min after ACTH stimulation; basal steroid profile was measured by LC-MS/MS. RESULTS: Genotyping revealed 23 21-NCAH, 15 single allele heterozygous CYP21A2 mutations (21-HTZ) and 32 PCOS patients displaying similar clinical and metabolic features. Immunoassays revealed higher baseline 17OHP and testosterone, and after ACTH stimulation, higher 17OHP (17OHP60) and lower cortisol, whereas LC-MS/MS revealed higher 17OHP (17OHPLC-MS/MS), progesterone and 21-deoxycortisol and lower corticosterone in 21-NCAH compared with both 21-HTZ and PCOS patients. Steroid thresholds best discriminating 21-NCAH from 21-HTZ and PCOS were estimated, and their diagnostic accuracy in identifying 21-NCAH from PCOS was established by ROC analysis. The highest accuracy was observed for 21-deoxycortisol ≥ 0.087 ng/mL, showing 100% sensitivity, while the combination of 17OHPLC-MS/MS ≥ 1.79 ng/mL and corticosterone ≤ 8.76 ng/mL, as well as the combination of ACTH-stimulated 17OHP ≥ 6.77 ng/mL and cortisol ≤ 240 ng/mL by immunoassay, showed 100% specificity. CONCLUSIONS: LC-MS/MS measurement of basal follicular 21-deoxycortisol, 17OHP and corticosterone seems the most convenient method for diagnosing 21-NCAH in a population of PCOS with a positive first level screening, providing high accuracy and reducing the need for ACTH stimulation test.

Assessment of the 21-hydroxylase deficiency and the adrenal functions in young females with Turner syndrome.

There are few reports of an association between Turner syndrome (TS) and 21-hydroxylase deficiency. However, this association is more frequent in some populations. The aim of this study was to evaluate the incidence of 21-hydroxylase deficiency in patients with TS in our population. 21-hydroxylase deficiency was evaluated in 44 TS cases with 45X (n=20) and 24 mosaic cases. A standard dose adrenocorticotropic (ACTH) stimulation test (Synacthen, Novartis, Basel, Switzerland) was performed, and 17 hydroxyprogesterone (17OHP), dehydroepiandrosterone sulfate (DHEAS) and cortisol responses were evaluated. Patients with increased 17OHP responses in the stimulation test also underwent 21-hydroxylase gene analysis. The mean age was 14.6 +/- 4 (2.6-22.4); 37 patients were on growth hormone (GH) treatment. Nine patients were at prepubertal stage, whereas 35 were pubertal (24 on gonadal steroids and 11 spontaneously). Six patients were obese. Only one of our patients had a level of 7.5 ng/mL of 17OHP, and there was no mutation found in congenital adrenal hyperplasia (CAH) genetic analysis. In other cases, peak 17OHP levels were < or = 6 ng/mL. The mean peak 17OHP was 2.62 +/- 1.48 (1.19-7.5) ng/mL, the cortisol level was 37.6 +/- 8.43 (23.9-56.2) microg/dL and the DHEAS was 135.2+/- 87.3 (15-413) microg/dL. The increased mean basal and peak cortisol levels (20.5 +/- 10.2 and 37.6 +/- 8.4 microg/dL) were remarkable findings. Whereas basal cortisol was above 20 microg/dL in 38.7% of patients, exaggerated results up to 56.2 microg/dL were obtained in peak cortisol levels. The basal and peak 17OHP cortisol levels were not correlated with the presence of puberty, chromosome structure, gonadal steroid use, obesity or growth hormone use. This trial suggested that 21-hydroxylase deficiency was not common among patients with TS in our population. Adrenal function should be assessed, at least in the presence of clitoral enlargement in patients with TS, particularly if their karyotype does not contain a Y chromosome.

Genetic determinants of 21-hydroxylase autoantibodies amongst patients of the Type 1 Diabetes Genetics Consortium.

BACKGROUND: Autoantibodies to 21-hydroxylase (21OH-AA) precede the onset of autoimmune Addison's disease (AD) and are found in 1.5% of individuals with type 1 diabetes mellitus (T1DM). The greatest genetic risk for both disorders is found in the major histocompatibility complex (MHC), suggesting a common pathophysiology between AD and T1DM. Screening for 21OH-AA in newly diagnosed T1DM patients is a valuable prognostic tool, made stronger when MHC genotype is considered. METHODS: The Type 1 Diabetes Genetics Consortium has collected genotype data in T1DM subjects with tissue-specific autoantibody typing. Genotype and phenotype data in individuals positive and negative for 21OH-AA are compared. RESULTS: Major genetic risk for 21OH-AA is in the MHC haplotypes DRB1*04-DQB1*0302 (primarily DRB1*0404) and DRB1*0301-DQB1*0201. Protective effects in class II MHC haplotypes DRB1*0101-DQB1*0501 and DRB1*0701-DQB1*0202 also were detected. There is no difference in the presence of HLA-B15 and little difference in the presence of HLA-B8 (after class II effects are accounted for) in T1DM patients with 21OH-AA compared with known associations (HLA-B8 positive and HLA-B15 negative) in AD. CONCLUSIONS: In 21OH-AA(+) subjects, genetic risk is found mainly in MHC class II haplotypes DR3 and DR4 but not class I alleles (HLA-B8 or HLA-B15). This suggests a difference between autoantibody formation (class II dependent) and progression to overt disease (class I dependent) in AD.

Consejo genético en la hiperplasia suprarrenal congénita por déficit de 21-hidroxilasa / Prenatal counselling of 21-hydroxylase deficiency

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Utilidad del análisis molecular en el diagnóstico diferencial del déficit congénito de 21-hidroxilasa detectado en el cribado neonatal / Usefulness of molecular analysis in the differential diagnosis of congenital 21-hidroxylase deficiency detected in neonatal screening

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Molecular genetics of 21-hydroxylase deficiency.

More than 95% of all cases of congenital adrenal hyperplasia are caused by deficiency of steroid 21-hydroxylase, an enzyme encoded by the CYP21A2 gene. The severity of the clinical symptoms varies according to the level of residual 21-hydroxylase activity. The CYP21A2 gene is located in the HLA class III region, as a component of so called RCCX modules containing homologous genes repeated in tandem. Misalignment followed by unequal crossing over as well as gene conversion events result in a high degree of variation in gene copy number as well as gene sequence in this genomic region. The presence of a highly homologous pseudogene, CYP21A1P, forms the basis for the relatively high incidence of 21- hydroxylase deficiency as deleterious sequences can be transferred from CYP21A1P to CYP21A2. Despite the complexity of the locus, safe approaches for genotyping are established, and genotype phenotype relationships have been documented making genotyping a valuable complement to biochemical investigations in the diagnostics of 21-hydroxylase deficiency. This is of particular importance in relation to family investigations and neonatal screening.

Expression of Cyp21a1 and Cyp11b1 in the fetal mouse testis.

Fetal Leydig cells and fetal adrenocortical cells may share a common progenitor cell. Both cell types show several similarities, particularly in relation to their primary steroidogenic function. Differences in steroid secretion are largely due to the expression of 21-hydroxylase (CYP21A1) and 11beta-hydroxylase (CYP11B1) activity in the adrenal. To determine whether expression of these enzymes defines a clear difference between adrenocortical and Leydig cells, or is further evidence of a link between the cell types, we have measured Cyp21a1 and Cyp11b1 expression and related enzyme activity in the fetal testis. Expression of both Cyp21a1 and Cyp11b1 was clearly detectable in the fetal testis by RT-PCR and Southern blotting. Real-time PCR studies showed that Cyp11b1 was expressed only in the fetal/neonatal testis with no expression in the pubertal or post-pubertal animal. Cyp21a1 was also predominantly expressed in the fetal testis although some lower expression was also seen in the adult. Expression of Cyp21a1 and Cyp11b1 in neonatal testicular cells was unaffected by incubation in vitro with human chorionic gonadotrophin or ACTH. Using immunohistochemistry, CYP21A1 was localised to a subset of interstitial steroidogenic cells in the fetal testis although CYP11B1 was not detectable. Incubation studies showed that 21-hydroxylase activity was present in the tissue although 11beta-hydroxylase activity could not be detected. Results indicate that a subpopulation of steroidogenic cells in the fetal testis express Cyp21a1 and show 21-hydroxylase activity. This may provide further evidence of a link between fetal Leydig cells and adrenocortical cells but does not discount the possibility that these steroidogenic cells represent 'ectopic' adrenal cells.

[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.

Metabolic profile and body composition in adult women with congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

CONTEXT: The chronic, often supraphysiological glucocorticoid doses used in congenital adrenal hyperplasia (CAH) might increase morbidity in cardiovascular disease and diabetes. OBJECTIVE: Our aim was to assess risk factors for cardiovascular disease and diabetes in CAH women. SUBJECTS, METHODS, AND DESIGN: We compared 61 women, 18-63 yr, with CAH due to 21-hydroxylase deficiency with 61 age- and sex- matched controls. Twenty-seven were younger than 30 yr, and 34 were 30 yr or older. Anthropometry, fat and lean mass measured by dual-energy x-ray absorptiometry, serum lipids, insulin, and adrenocortical steroids were studied. MAIN OUTCOME MEASURE: Body composition and cardiovascular risk factors were the main outcome measures. RESULTS: Younger patients and controls had similar waist to hip ratio, lean and fat mass, and insulin. Older patients had higher waist to hip ratio, lean mass, and insulin than controls. Fat mass was similar to controls but higher than in younger patients. Lipid profiles were slightly more favorable in older patients than controls. Gestational diabetes was more common in patients (21% of pregnancies vs. 0, P < 0.026). Few older patients had hypertension, cardiovascular disease, or diabetes. Despite moderate glucocorticoid doses, most patients had suppressed androgens. CONCLUSIONS: No clear evidence of unfavorable cardiovascular risk factors were found. Increased fat mass and higher insulin levels were, however, found in patients older than 30 yr. High frequency of gestational diabetes is a risk marker for future diabetes. Lifelong follow-up, lifestyle modifications, and attempts to adjust and reduce the glucocorticoid doses seem important.

Serum 21-Deoxycortisol, 17-Hydroxyprogesterone, and 11-deoxycortisol in classic congenital adrenal hyperplasia: clinical and hormonal correlations and identification of patients with 11beta-hydroxylase deficiency among a large group with alleged 21-hydroxylase deficiency.

INTRODUCTION: 21-Hydroxylase deficiency (21OHD) is the most common cause of congenital adrenal hyperplasia, followed in frequency by 11beta-hydroxylase deficiency (11betaOHD). Although the relative frequency of 11betaOHD is reported as between 3 and 5% of the cases, these numbers may have been somewhat underestimated. MATERIALS AND METHODS: In 133 patients (89 females/44 males; 10 d-20.9 yr) with alleged classic 21OHD and five (three females/two males; 7.3-21 yr) with documented 11betaOHD, we measured serum 21-deoxycortisol (21DF), 17-hydroxyprogesterone (17OHP), and 11-deoxycortisol (S), 48 h after glucocorticoid withdrawal. We also studied 20 sex- and age-matched control subjects. Serum steroid levels were determined by RIA after HPLC purification. OBJECTIVES: The objectives of this study were to: 1) quantify 21DF in patients with congenital adrenal hyperplasia, 2) correlate hormonal with clinical data, and 3) identify possible misdiagnosed patients with 11betaOHD among those with 21OHD. RESULTS: In 21OHD, 17OHP (217-100,472 ng/dl) and 21DF (<39-14,105 ng/dl) were mostly elevated and positively correlated (r = 0.7202; P < 0.001). Except for higher 17OHP in pubertal patients, 17OHP and 21DF values were similar according to sex, disease severity, or prevailing glucocorticoid dose. One additional patient with 11betaOHD was detected (1%) and also one with apparent combined 11beta- and 21OHD. S levels were elevated in 11betaOHD and normal but significantly higher in 21OHD than in controls. CONCLUSION: To recognize patients with 21- and/or 11betaOHD, we recommend evaluation of 17OHP or 21DF and S. Also, 21DF may be useful to follow up pubertal patients with 21OHD. Because 1% of patients with alleged 21OHD may have 11betaOHD, its frequency seems underestimated, as per our experience in a Brazilian population.

Déficit de 21-hidroxilasa: aspectos actuales / 21-hydroxylase deficiency: current aspects

La hiperplasia suprarrenal congénita (HSC) es una de las alteraciones autosómicas recesivas más frecuentes. Caracterizada por un defecto enzimático en la síntesis de cortisol, la causa es, en el 95% de los casos, la deficiencia de la enzima 21-hidroxilasa (21-OH). La 17-OH progesterona, precursor del cortisol, presenta valores elevados, marcadores del diagnóstico. Esta enfermedad presenta diferentes formas clínicas; las clásicas o graves comienzan desde el período neonatal, con síntomas debidos al exceso de andrógenos suprarrenales como virilización y ambigüedad de los genitales externos de las niñas afectadas. En más del 70% de los casos se asocia pérdida salina (deficiencia de aldosterona), potencialmente letal en varones que no se diagnostican precozmente. Resumimos las diferentes formas de presentación de la deficiencia de 21-OH, y describimos el diagnóstico y el tratamiento con gluco y mineralcorticoides, con especial énfasis en la importancia de utilizar dosis de estrés de hidrocortisona, cuando es necesario. Los avances quirúrgicos actuales ofrecen una corrección funcional de las pacientes afectadas. Los programas de detección precoz evitan la asignación incorrecta de sexo en la recién nacida y pueden salvar la vida de los varones con formas graves y pérdida salina. Comentamos el diagnóstico genético-molecular del CYP21A2 (cromosoma 6p 21.3) y las características en la población española. Revisamos las directrices futuras para el estudio y el tratamiento de esta enfermedad, incluyendo diversos tratamientos como la flutamida, la hormona de crecimiento, los antagonistas de las gonadotropinas o la relación con el síndrome de ovario poliquístico. El diagnóstico y el tratamiento prenatales del feto femenino afectado son posibles, y los resultados son alentadores. Comentamos, también, el abordaje hacia la transición y la edad adulta, y la relevancia del control de la mujer con HAC durante la gestación

Congenital adrenal hyperplasia (CAH) is one of the most frequent autosomal recessive disorders. It is characterized by a deficiency of an enzyme involved in cortisol synthesis and in 95% of patients the cause is 21-hydroxylase deficiency. A diagnostic marker is elevated levels of 17-hydroxyprogesterone, a precursor of cortisol. CAH has several clinical forms, and classical or severe forms manifest in the neonatal period with symptoms due to excess adrenal androgen production such as virilization and ambiguity of the external genitalia in affected girls. In more than 70% of patients, there is associated salt wasting (aldosterone deficiency), which can be fatal in males without an early diagnosis. We summarize the various forms of presentation of 21-hydroxylase deficiency and describe diagnosis and treatment with gluco- and mineralocorticoids, with special emphasis on the importance of using stress doses of hydrocortisone when necessary. Current surgical advances provide functional correction in affected patients. Screening programs avoid incorrect sex assignment in the newborn and can save the lives of males with severe forms and salt wasting. We discuss the genetic-molecular diagnosis of CYP21A2 (chromosome 6p 21.3) and its characteristics in the Spanish population. We review future recommendations for the study and management of this disease, including several treatments such as flutamide, growth hormone, and gonadotrophin antagonists, as well as the association with polycystic ovary syndrome. Prenatal diagnosis and treatment in affected female fetuses are feasible and the results are encouraging. We also discuss the management of the transition to adulthood and the importance of follow-up of women with CAH during pregnancy

[Histological and molecular study of fetal human adrenal cortex (12-36 wk)]. / Etude histologique et moléculaire de la corticosurrénale foetale humaine (12e-36e SD). La corticosurrénale foetale humaine (12e-36e SD).

Histological and functional characteristics of the fetal human adrenals was studied in 119 normal fetuses aged 12 to 36 weeks development (WD). Immunocytochemical detection of steroidogenesis enzyme (3beta-HSD and P450 c21) and evaluation of cell proliferation using two nuclear markers (Ki-67 and PCNA) were performed in 70 of them. The human fetal adrenal cortex is composed of two morphologically distinct zones: the definitive peripheral zone and the fetal inner zone. From the 12th WD, we observed expression of an adherence protein (NCAM) and two steroidogenesis enzymes (3beta-HSD and P450 c21) in the definitive zone cells, attesting to the capacity of these cells to synthesize mineralocorticoids and/or cortisol. In the fetal zone, only P450 c21 immunoreactivity was detected. From the 14th WD, a transitional zone between the definitive zone and the fetal zone was identified by immunocytochemistry, with expression of 3b-HSD from the 21st WD. Only cells of the definitive zone proliferated from the 12th to 25th WD. The indexes of proliferation of PCNA and Ki-67, 40% and 25% respectively, decreased gradually and were lower than 1% at the 25th WD.

Prevalencia de enfermedades recesivas frecuentes en población española mediante análisis de ADN en muestras del cribado neonatal / Prevalence of frequent recessive diseases in the Spanish population through DNA analyses on samples from the neonatal screening

Fundamento y objetivo: La fibrosis quística (FQ) y las formas no clásicas de hiperplasia suprarrenal congénita por deficiencia de 21-hidroxilasa (NC21OHD) son enfermedades autosómicas recesivas frecuentes. En su estudio se utilizan las frecuencias descritas para población caucásica (1:2.500 y 1:1.000, respectivamente). Nos planteamos conocer si estos datos son aplicables a nuestra población. Material y método: Determinación de las frecuencias de las mutaciones recurrentes (~ 50%) de cada entidad, DF508 y Val281Leu, en 300 muestras (600 alelos) consecutivas y anónimas del cribado neonatal. Se realizaron una amplificación de los genes CFTR y CYP21A2 y un análisis directo de las mutaciones. Resultados: Las frecuencias alélicas para DF508 y Val281Leu han sido de 0,005 y 0,038, respectivamente (frecuencia de portadores: un 1,1 y un 7,5%). Considerando que estas mutaciones suponen un 48% (FQ) y un 57% (NC21OHD) de los alelos en pacientes, se estiman unas prevalencias medias de 1:8.028 (FQ) y 1:230 (NC21OHD). Los errores estándar para estos datos son del 0,6 y del 1,5%, respectivamente. Conclusiones: En nuestra población, la FQ tiene una menor frecuencia y la NC21OHD es más prevalente, por lo que no pueden extrapolarse los datos de frecuencia obtenidos en otras poblaciones caucásicas

Background and objective: Cystic fibrosis (CF) and the nonclassical forms of congenital adrenal hyperplasia (NC21OHD) are frequent autosomal recessive diseases. Their frequencies in the Caucasian population are the ones applied to the management of the diseases (1:2500 and 1:1000, respectively). The aim of this study was to learn about the adequacy of these figures to the Spanish population. Material and method: Study of the recurrent mutation (about 50% of alleles) in each entity, DF508 or Val281Leu, respectively, in 300 anonymous consecutive samples (600 alleles) from the Comunidad de Madrid neonatal screening. PCR specific amplifications of the CFTR and CYP21A2 genes and direct analyses of DF508 and Val281Leu mutations were performed. Results: Allele frequencies of DF508 and Val281Leu were 0.005 and 0.038 (carrier frequencies 1.1% and 7.5%, respectively). Taking into consideration the percentage of these mutations in patient alleles, 48% for CF and for 57% NC21OHD, disease frequencies of about 1:8028 (CF) and 1:230 (NC21OHD) were estimated. The standard error calculated for these data were 0.6% and 1.5%. Conclusions: We have found that CF is less frequent and NC21OHD more frequent in the Spanish population than in other Caucasian populations

Hiperplasia suprarrenal congénita por déficit de 21-hidroxilasa. ¿Cuándo es necesario conocer el genotipo? / Congenital adrenal hyperplasia due to 21-hydroxilase deficiency: when should we know the genotype?

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Cytochrome P450 2D catalyze steroid 21-hydroxylation in the brain.

mRNA of cytochrome P450 21-hydroxylase (P450c21) is expressed in the brain, but little is known about the enzymatic properties of P450c21 in the brain. In the present study, we showed, by using various recombinant cytochrome P450 (CYP)2D enzymes and anti-CYP2D4- or P450c21-specific antibodies, that rat brain microsomal steroid 21-hydroxylation is catalyzed not by P450c21, but by CYP2D isoforms. Rat CYP2D4 and human CYP2D6, which are the predominant CYP2D isoforms in the brain, possess 21-hydroxylation activity for both progesterone and 17alpha-hydroxyprogesterone. In rat brain microsomes, these activities were not inhibited by anti-P450c21 antibodies, but they were effectively inhibited by the CYP2D-specific chemical inhibitor quinidine and by anti-CYP2D4 antibodies. mRNA and protein of CYP2D4 were expressed throughout the brain, especially in cerebellum, striatum, pons, and medulla oblongata, whereas the mRNA and protein levels of P450c21 were extremely low or undetectable. These results support the idea that CYP2D4, not P450c21, works as steroid 21-hydroxylase in the brain. Allopregnanolone, a representative gamma-aminobutyric acid receptor modulator, was also hydroxylated at the C-21 position by recombinant CYP2D4 and CYP2D6. Rat brain microsomal allopregnanolone 21-hydroxylation was inhibited by fluoxetine with an IC(50) value of 2 microm, suggesting the possibility that the brain CYP2D isoforms regulate levels of neurosteroids such as allopregnanolone, and that this regulation is modified by central nervous system-active drugs such as fluoxetine.

Monitoring of menstrual cycles, ovulation, and adrenal suppression by saliva sampling in female patients with 21-hydroxylase deficiency.

OBJECTIVE: To investigate the correlation between menstrual cycles, ovulation, and adrenal suppression in congenital adrenal hyperplasia. DESIGN: Prospective observational study. SETTING: An academic outpatient clinic. PATIENT(S): Five females with salt-wasting 21-hydroxylase deficiency, aged 15.5 to 22.9 years; one had amenorrhea, one had irregular bleeding, and three had regular bleeding. INTERVENTION(S): Daily morning saliva sampling for 40 to 280 days. MAIN OUTCOME MEASURE(S): Salivary levels of progesterone (P), 17-hydroxyprogesterone (17-OHP), and androstenedione. RESULT(S): In the amenorrheic patient, the elevated P and 17-OHP levels decreased when the glucocorticoid dose was increased, and subsequently menarche occurred. The androstenedione levels were normal. The correlations between P and 17-OHP levels before and after menarche suggest that adrenal progesterone had prevented menarche. The patient with irregular bleeding showed slightly elevated androstenedione levels and increased levels of 17-OHP and P in an irregular pattern, without correlation in time with vaginal bleeding. Three patients with regular cycles showed a biphasic pattern of P levels, indicating ovulation. CONCLUSION(S): These longitudinal data support the hypothesis that menstrual cycling in females with 21-hydroxylase deficiency can be prevented or disturbed by elevated progesterone levels of adrenal origin, in the absence of androgen excess. Increasing glucocorticoid dose could suppress adrenal progesterone production, resulting in menarche.

Estado en la edad adulta y propuesta de optimización terapéutica de la hiperplasia suprarrenal congénita / No disponible

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Characterization of pathogenic mutations in 21-hydroxylase gene of Pakistani patients with congenital adrenal hyperplasia and their family members--a preliminary report.

OBJECTIVE: To characterize specific mutations within the 21-hydroxylase gene (CYP21-B) using ARMS-PCR assay in patients with congenital adrenal hyperplasia (CAH) and to compare it with that reported in other populations. SUBJECTS AND METHODS: Five families, having an index case with CAH diagnosed on the basis of clinical and biochemical findings volunteered to give blood samples for analysis. A strategy, based on ARMS-PCR (Amplified Refractory Mutation System) was employed for the detection of mutations in 21-hydroxylase gene. The products of ARMS-PCR were resolved on agarose gels and the PCR products were visualized over ultra violet illumination. RESULTS: Twenty-six specimens were analyzed for common point mutations in the 21-hydroxlase genes at the nucleotide positions 659, 1004 and 1688. Seven samples belonged to index cases with CAH. Of these 7, the assigned sex was male in 5 and female in 2 cases. However, genotypic sex was 3 males and 4 females. The mean age was 8 months in 5 cases while the median 17-OH Progesterone levels was 273.2 ng/ml. Vomiting, precocious puberty and ambiguous genitalia were the presenting features in 2, 1 and 4 cases respectively. Analysis for mutation at 659, 100 and 1688 was performed on 7 index cases and the family members of 5 index cases. The mutation analysis for the family members of index case 6 and 7 was not performed due to non-availability of their blood specimens. Index case No. 1, 4 and 7 showed homozygosity for splice mutations at nucleotide position 659, intron 2 with a sequence change of A to G, while the index case No. 2 and 6 showed heterozygosity for the same mutation. No mutation was found at 659, 1004 or 1688 in index case No. 3 and 4 at the analyzed nucleotide position. Nineteen family members of Case Nos. 1-5 were also analyzed for the same mutations. (Family No. 1, 2, 3, 4 and 5 included 3, 2, 7, 4 and 5 members respectively). These included 8 males and 11 females. All were asymptomatic. Both the parents of index case 1 and 4 were heterozygous at 659 while the father of index case No. 2 was heterozygous at 659 and mother was normal. CONCLUSION: Our results demonstrated the A to G transition at nucleotide 659 causing aberrant splicing, reported for some other populations as the most commonly identified point mutations. All cases were appropriately assigned to paternal or maternal chromosomes.