21-OHD Patients Research Articles

The Common P450 Oxidoreductase Variant A503V Is Not a Modifier Gene for 21-Hydroxylase Deficiency

21-hydroxylase deficiency (21OHD) is a common genetic disorder caused by mutations in the CYP21A2 gene, which encodes the adrenal 21-hydroxylase, microsomal P450c21. CYP21A2 gene mutations generally correlate well with impaired P450c21 enzymatic activity and the clinical findings in 21OHD, but occasional discrepancies between genotype and phenotype suggest the effects of modifier genes. Mutations in P450 oxidoreductase (POR), the protein that transfers electrons from reduced nicotinamide adenine dinucleotide phosphate to all microsomal P450s, can ameliorate the 21OHD phenotype and, therefore, could be a modifier gene. We sought to identify POR variants in patients with 21OHD having discordant phenotype and genotype, and to evaluate their effect on 21-hydroxylase activity. We determined the CYP21A2 genotypes of 313 Brazilian patients with 21OHD and correlated the genotype and phenotype. The POR gene was sequenced in 17 patients with discordant genotype and phenotype. Wild-type and A503V POR, and P450c21 were expressed in bacteria and reconstituted in vitro. Activities were assayed by conversion of [(14)C]progesterone to deoxycorticosterone and [(3)H]17-hydroxyprogesterone to 11-deoxycortisol, and assessed by thin layer chromatography and phosphorimaging. The A503V POR variant was found in 10 of 30 alleles, the same ratio as in the normal population. There were no significant differences in Michaelis constant, maximum velocity and maximum velocity/Michaelis constant of 21-hydroxylase activity supported by wild-type and A503V POR. The only POR missense polymorphism found in atypical 21OHD patients was A503V. Although A503V reduces P450c17 enzymatic activity, it does not influence P450c21 activity, indicating that POR A503V does not modify the 21OHD phenotype.

Nonclassic Steroid 21-Hydroxylase Deficiency due to a Homozygous V281L Mutation in CYP21A2 Detected by the Neonatal Mass-Screening Program in Japan

Since 1989, neonatal mass screening for congenital adrenal hyperplasia (CAH) has been carried out in Japan. The mass screening has detected not only the patients with the classic form of steroid 21-hydroxylase deficiency (21-OHD), but also those with the nonclassic (NC) form of 21-OHD, and the molecular basis in these patients has been elucidated. However, the homozygous V281L mutation in CYP21A2, the common mutation in the NC form in Caucasians, has not been described in Japanese patients, implying at least two possibilities; 1) the V281L mutation itself might be very rare in Japanese, and 2) nonclassic 21-OHD patients bearing the V281L mutation might be barely detectable by the mass-screening program, hence overlooked in Japan. In the present study, we describe a Brazilian girl with the NC form of 21-OHD, who was pointed out to have mildly elevated 17 alpha-hydroxyprogesterone in blood by the mass screening in Japan. Genetic analysis revealed that the patient was homozygous for the V281L mutation, and that the parents were heterozygous for the V281L mutation. Thus, the NC patients due to the homozygous V281L mutation can be detectable by the mass-screening program for CAH in Japan, and further accumulation and analysis of the NC patients should elucidate the frequency of the V281L allele in Japan.

Gene duplications in 21-hydroxylase deficiency: the importance of accurate molecular diagnosis in carrier detection and prenatal diagnosis

The detection of 21-OH deficiency (21OHD) carriers in the general population requires that misinterpretations of apparently severe mutations in alleles carrying duplicated genes be avoided. Prenatal treatment prevents virilization in female fetuses and genetic counseling may be offered to couples in which one partner is either a patient or a carrier. This paper proposes a semiquantitative PCR method involving primer extension that distinguishes the severe point mutation Q318X in single gene copy alleles from the normal/nondeficient variant in gene-duplicated alleles. DNA from 65 individuals carrying Q318X variants, that of 85 partners of 21OHD carriers or patients, and one fetal sample (as well as the DNA of his family) were analyzed. 21OHD alleles were studied by gene-specific PCR/allele-specific oligonucleotides hybridization for common mutations, Southern analysis, complementary direct sequencing and microsatellite typing. Primer extension analysis of the Q318X variants using fluorescent dideoxynucleotides was performed on CYP21A2 gene-specific PCR-amplified DNA samples from controls, patients, potential carriers and prenatal samples. Different fluorescence patterns were seen for the severe mutation (single gene copy) and the nondeficient (gene-duplicated) alleles carrying Q318X. The normal/mutant fluorescence peak (N/M) ratio was < 1 in all heterozygous carriers (mean 0.83; min. 0.70; max. 0.95). In all normal individuals carrying the gene-duplicated Q318X normal variant, the N/M ratio was > 1 (mean 1.69; min. 1.44; max. 2.02). The proposed method discriminated between the severe Q318X mutation and the normal Q318X variant in gene duplication, and could be a useful complementary tool in prenatal diagnosis and carrier detection.

The interaction of plasma renin activity and plasma atrial natriuretic peptide in 21-hydroxylase deficiency patients

Plasma renin activity (PRA) determination is the main index used to evaluate the mineralocorticoid control in 21-hydroxylase deficiency (21-OHD). PRA values within or at the upper limit of the age-appropriate range, or values <5 or 10 ng/ml/h have been regarded as adequate control. Atrial natriuretic peptide (ANP) has opposite actions to those of angiotensin II/aldosterone, and could help to understand the hydrosaline homeostasis in 21-OHD. We studied the interaction between PRA and ANP levels in 10 controls and 26 patients with 21-OHD under corticoid treatment. Patients were divided into two groups according to PRA levels, < or > or = 5 ng/ml/h, irrespective of the clinical form of 21-OHD. Blood samples for determination of PRA and ANP levels were taken after 30 min in the sitting position (basal), after 30 min in the recumbent position and after 15 min of 20 degrees head-down tilting. ANP levels (pg/ml) in the basal, supine and after head-down tilting position were 25.9 +/- 1.6, 42.7 +/- 7.4 and 54.3 +/- 5.5 in controls; 28.5 +/- 2.1, 38.3 +/- 2.1 and 48.8 +/- 4.1 in the group with PRA levels <5 ng/ml/h, and 20.9 +/- 1.9, 26.6 +/- 2.5 and 34.6 +/- 3.1 in the group with PRA levels > or = 5 ng/ml/h, respectively. Basal and after head-down tilting ANP plasma levels were similar between the controls and the group with PRA levels <5 ng/ml/h. However, the group of patients with PRA levels > or = 5 ng/ml/h showed lower basal and stimulated ANP levels compared to the control group (p<0.05). The decreased plasma ANP levels in the basal condition and after head-down tilting indicate a chronic contraction of the extracellular volume in 21-OHD patients with increased PRA levels. Therefore, mineralocorticoid deficiency is counteracted by decreased ANP secretion in order to preserve fluid and electrolyte homeostasis.

Limited value of serum steroid measurements in identification of mild form of 21-hydroxylase deficiency.

ACTH stimulation test is widely used as a basic diagnostic method for non-classical congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD). However, the interpretation of this test has not been definitely established. To determine the cut-off values of basal and post-ACTH serum 17-OHP concentrations, data of patients with suspected 21-OHD has been analysed. Two hundred and eighty-seven patients with postnatal/peripubertal virilization were investigated. Serum steroid concentrations were measured by RIA, urinary steroid profile was determined by capillary gas chromatography and mutation analysis of CYP21 gene was performed by allele specific PCR. 21-OHD was diagnosed by elevated serum 17-OHP concentrations, high level of the urinary 17-OHP metabolites and/or homozygosity for CYP21 mutations. Twenty-one patients of the total of 287 subjects (7.3 %) were identified as having 21-OHD. The numbers of 21-OHD patients compared to total numbers of patients with different ranges of serum 17-OHP were as follows: basal values below 3.5 ng/ml (mean + 1 SD) 0/225; between 3.5 - 6.6 ng/ml 3/41; above 6.6 ng/ml (mean + 2 SD) 18/21. Post-ACTH values below 6.4 ng/ml (mean + 1 SD) 0/226, between 6.4 - 10.3 ng/ml 0/35, above 10.3 ng/ml (mean + 2 SD) 21/26. There are patients with inappropriate peripubertal virilization who have slightly elevated 17-OHP concentrations. In this subgroup of patients more sensitive and specific methods are needed to establish the diagnosis of 21-OHD. Therefore we suggest performing an ACTH stimulation test in patients with a morning 17-OHP level above 3.5 ng/ml. Furthermore, urinary steroid profile and/or CYP21 gene analysis are needed in patients with a stimulated 17-OHP value between 10 and 30 ng/ml. These tests will distinguish between patients with non-classical 21-OHD and patients with other disorders.

Mortality in Patients with Congenital 21-Hydroxylase Deficiency Diagnosed after the Introduction of a Newborn Screening Program in Japan

In order to estimate the mortality in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21OHD) diagnosed after the introduction of a newborn screening program in Japan, a questionnaire was sent to all members of the Japanese Society for Pediatric Endocrinology. Three hundred and eighty two out of 960 questionnaires were available for the analysis. Twelve deaths were reported. Two died in an early neonatal period, and 10 patients were on maintenance therapy. This suggests that mortality is estimated to be one in 25-80 21OHD patients on maintenance therapy in childhood. It was speculated that cortisol deficiency somewhat contributed to their deaths. Of note, 4 died during a gastrointestinal infection. The need to increase hydrocortisone doses, and the importance of parenteral hydrocortisone administration during stress or illnesses should be repeatedly informed to carers and their physicians.

Neonatal screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency. 4. Development of enzyme-linked immunosorbent assay for dried blood cortisol and its application to neonatal screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency

An enzyme-linked immunosorbent assay (ELISA) for Cortisol in dried blood collected on filter paper has been developed. The ELISA method is very simple and rapid and has sensitivity, accuracy and precision. The detection limit of the ELISA is 10 ng/ml blood. The intra- and interassay coefficients of variation are 11.5-13.5% and 15.7-16.7, respectively. Using the ELISA for Cortisol and 17-hydroxyprogesterone (17-OHP) previously reported, dried blood from normal newborns including premature infants (n = 1583) and 21-hydroxylase deficiency (21-OHD) patient (n = 9) were analyzed. 17-OHP, Cortisol and 17-OHP/Cortisol ratio of normal newborns are 12.5 +/- 7.5 ng/ml (1.0-140 ng/ml), 89.0 +/- 64.3 ng/ml (10-1580 ng/ml) and 0.16 +/- 0.08 (0.01-0.86), respectively. In 21-OHD patients, 17-OHP is 109-1361 ng/ml, Cortisol is 35.1-146.7 ng/ml and 17-OHP/cortisol ratio is 1.84-12.2. It made recall rate less to measure Cortisol in addition to 17-OHP and to take 17-OHP/Cortisol ratio. Therefore, additional measurement of Cortisol to the primary 17-OHP screening test is advantaged in differentiating the normal newborns from the 21-OHD patients.