Clinical and endocrinological aspects of 21-hydroxylase deficiency

Congenital adrenal hyperplasia: molecular genetics and alternative approaches to treatment

Several autosomal recessive disorders affecting the adrenal cortex and its development and leading to defective cortisol biosynthesis are known under the collective term "congenital adrenal hyperplasia" (CAH). Over the last two decades, the genes causing most of these disorders have been identified and molecular genetics may supplement their clinical and biochemical diagnosis. In addition, new treatments have emerged; although gene therapy has yet to be applied in humans, studies are ongoing in gene transfer in adrenocortical cell lines and animal models. In this review, after a brief introduction on the developmental biology and biochemistry of the adrenal cortex and its enzymes, we will list the new developments in the genetics and treatment of diseases causing CAH, starting with the most recent findings. This order happens to follow adrenal steroidogenesis from the mitochondrial entry of cholesterol to cortisol synthesis; it is unlike other presentations of CAH syndromes that start with the most frequently seen syndromes, because the latter were also the first to be investigated at the genetic level and have been extensively reviewed elsewhere. We will start with the latest syndrome to be molecularly investigated, congenital lipoid adrenal hyperplasia (CLAH), which is caused by mutations in the gene coding for the steroidogenic acute regulatory (StAR) protein. We will then present new developments in the genetics of 3-beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 hydroxylase and 17,20-lyase (P450c17), 11 hydroxylase (P450c11 beta), and 21 hydroxylase (P450c21) deficiencies. Alternative treatment approaches and gene therapy experiments are reviewed collectively in the last section, because they are still in their infantile stages.

Elevated serum progesterone concentrations during the early follicular phase of the menstrual cycle: clinical significance and therapeutic implications

This study describes the incidence and clinical significance of hyperprogesteronemia in the early follicular phase of the menstrual cycle and the effects of prednisolone treatment in patients with this condition. Progesterone, testosterone and dehydroepiandrosterone sulfate (DHEAS) serum concentrations were determined in 316 consecutive patients admitted for infertility treatment. Elevated concentrations of progesterone in the early follicular phase could be detected in 36 cases (11.4%). In these patients, elevated testosterone and DHEAS concentrations could be detected in eight and ten cases, respectively. Serum concentrations of 17 alpha-hydroxyprogesterone and cortisol were normal in all patients. Treatment with 2.5-7.5 mg prednisolone/day normalized progesterone serum concentrations within 4-8 weeks. Twenty-four patients achieved a pregnancy either by timed intercourse or by intrauterine insemination (IUI) over the following 12 months.

Results of screening 1.9 million Texas newborns for 21-hydroxylase-deficient congenital adrenal hyperplasia

OBJECTIVE

To assess results of newborn screening for 21-hydroxylase-deficient congenital adrenal hyperplasia (CAH) in Texas over 6 years of screening 1.9 million infants.

METHODS

In 1989, CAH was incorporated into the ongoing Texas Newborn Screening Program, which requires two screens on each newborn. 17-Hydroxyprogesterone was assayed, without extraction, by radioimmunoassay of blood collected from heel sticks onto filter paper collection cards. Infants with elevated levels of 17-hydroxyprogesterone were referred for evaluation, and those considered to have CAH were studied with respect to disease characteristics. Data were collected by pediatric endocrinologists using standardized forms that included type of CAH, results of laboratory tests, treatment regimen, disease symptoms and signs, and, for girls, degree of genital virilization.

RESULTS

The incidence of classic CAH in Texas is 1:16 008, with a ratio of salt-wasting to simple-virilizing of 2.7:1. A majority of infants detected were undiagnosed until screened, despite signs of salt-wasting or ambiguous genitalia. It was difficult to differentiate salt-wasting from simple-virilizing CAH in infants who were identified before the onset of adrenal insufficiency or electrolyte abnormalities. A substantial number of infants with nonclassic (NC) CAH also were detected. Not all infants were detected on the initial screen; 14% of infants with classic CAH and 87% with NC CAH were detected on the second routine screening test.

CONCLUSIONS

Our findings confirm the benefits of newborn screening for CAH and the importance of a second screening test, and suggest that programs for newborn CAH screening must consider complex issues in diagnosis and treatment. These results also confirm that CAH is a continuum of disorders, rather than a disorder with discrete subtypes. In addition, the difficulties in differentiating CAH subtypes in newborns, and thus deciding appropriate treatment, and the high incidence of NC CAH suggest that standard diagnostic criteria and treatment regimens for CAH may need modification. Where screening exists, physicians will encounter more cases of CAH than in the past.

A contribution to the classification of cases of non-classic 21-hydroxylase-deficient congenital adrenal hyperplasia

The aim of this study was to classify the degree of 21 alpha-hydroxylase deficiency in patients suspected for non-classic 21-hydroxylase-deficient congenital adrenal hyperplasia (CAH). In 66 selected subjects (45 young women with polycystic ovary (PCO)-like symptoms and members of their families, of whom 12 were men), progesterone, 17-hydroxyprogesterone (17-OHP) and cortisol were measured at 0, 15, 30, 45 and 60 min after adrenocorticotropic hormone (ACTH) stimulation. The markers [(17-OHP at 30 min--17-OHP at 0 min) + (progesterone at 30 min--progesterone at 0 min)]/30 proposed by Gutai and the ratio of cortisol to 17-OHP at 30 min (cortisol30/17-OHP30) were calculated and cluster analysis was performed using the above two markers and 17-OHP at 60 min (17-OHP60). Our patients were grouped by cluster analysis into four Groups: I, II, III and IV (n = 3, 11, 35 and 16, respectively) with (1) Gutai (mean +/- SE) 107.0 +/- 21.7, 29.9 +/- 4.4, 10.5 +/- 0.54 and 4.0 +/- 0.37 ng/dl per min, respectively, (2) 17-OHP60 169.7 +/- 28.3, 10.8 +/- 1.3, 4.6 +/- 0.2 and 3.7 +/- 0.4 ng/ml, respectively, and (3) cortisol/17-OHP30 0.97 +/- 0.28, 38.5 +/- 6.9, 82.3 +/- 5.5 and 112.0 +/- 8.9, respectively. All three markers showed highly significant differences between the four groups (p < 0.0001). The patterns of 17-OHP, cortisol and cortisol/17-OHP ratio following ACTH testing revealed the degree of 21-hydroxylase deficiency in every group. HLA typing effected in 20 studied individuals confirmed the classification derived from cluster analysis. Thus, it seems that Groups I, II and III include, respectively, patients with severe, mild and minimal forms of non-classic 21-hydroxylase-deficient CAH, while in patients of Group IV the hyperandrogenemic symptoms are of different etiology. In conclusion, the concurrent evaluation of the three markers together with the variations of 17-OHP, cortisol and the cortisol/17-OHP ratio after ACTH testing enhance the accurate identification of a patient suspected for non-classic 21-hydroxylase-deficient CAH in relation to the severity of the enzymatic defect.

Diagnosis of classical steroid 21-hydroxylase deficiency using an HLA-B locus-specific DNA-probe

The HLA-B and steroid 21-hydroxylase loci are known to be closely linked. Restriction fragment length polymorphisms seen after digestion of genomic DNA with MspI and TaqI with the HLA-B locus-specific DNA-probe, pHLA-1.1, were examined in 7 nuclear families with classical steroid 21-hydroxylase deficiency. In each family 2 polymorphic hybridizing bands (corresponding to the 2 HLA-B genes) were seen. In all families, TaqI-generated polymorphisms allowed for identification of children previously shown on clinical and biochemical criteria to be affected by 21-hydroxylase deficiency from their unaffected sibs. The results were in complete agreement with the clinical diagnoses. Among the unaffected children, carriers could be distinguished from non-carriers in all cases by TaqI polymorphisms. MspI-generated polymorphisms allowed for full identification of genotypes in 5 families. In one family, MspI-generated polymorphisms could be used to identify affected from unaffected children, but could not distinguish between carriers and non-carriers. In another family, no identification of genotypes was possible by MspI-generated polymorphisms alone. The HLA-B locus-specific DNA-probe, pHLA-1.1, can be used for diagnosis and genotyping of individuals from families with 21-hydroxylase deficiency. This technique can be used as an alternative to HLA-serotyping, or in situations where HLA-serotyping is technically difficult, for example in chorionic villus samples.

Further evidence that there is more than one adrenal 21-hydroxylase system

The 21-hydroxylase activity of microsomes isolated from bovine adrenal cortex have been assayed using [21-3H]17-hydroxypregnenolone and [1,2-3H]17-hydroxyprogesterone as substrates. When the assays are performed in the presence of an NADH regenerating system, to inhibit steroid 3 beta-hydroxy isomerase-dehydrogenase activity, the microsomes oxidize the 3 beta-hydroxy-5-ene steroid at a rate of 0.37 nmol/min.nmol cytochrome P-450 and the 3-keto-4-ene steroid at a rate of 6.4 nmol/min.nmol. When the microsomes are solubilized with Triton CF-54 they lose the ability to oxidize the 3-hydroxy-5-ene steroid, while the specific activity of the microsomes for the 3-keto-4-ene steroid is enhanced 3-fold. In contrast, when the microsomes are solubilized with sodium cholate, their specific activity towards the 4-ene steroid is decreased by 50% while the specific activity for a low concentration of the 5-ene steroid, 1 microM, is unchanged. In addition, when the oxidations of the labeled steroids (at 1 microM) by the microsomes, are examined in the presence of unlabeled 17-hydroxyprogesterone (at 20 microM) the oxidation of the 3-keto-4-ene steroid is inhibited by 92% while the oxidation of the 3 beta-hydroxy-5-ene steroid is only inhibited by 20%. These results all suggest that there are at least two 21-hydroxylases in bovine adrenal tissue, one of which can utilize the 3-keto-4-ene steroids only, the other of which, in addition, can utilize the 3 beta-hydroxy-5-ene steroids as substrates.

Gender dysphoria in a child with true hermaphroditism

This case report describes the psychosexual development of a child with true hermaphroditism who was assigned to the male sex at birth, but reassigned to the female sex at age two months. Given this child's excessive exposure to male sex hormone in utero, relative to physically normal females, one would predict a biological predisposition to behave in a masculine manner. This has occurred since two years of age. In addition, this child has had periodic episodes of gender disturbance, dysphoria, and ambivalence. In contrast, a physically normal fraternal twin sister has been conventionally feminine. A number of psychosocial factors appeared to have exacerbated the biologic predisposition to behave in a masculine manner, and thus may have been responsible for "pushing" this child into varying degrees of gender identity conflict. These included a closer father-daughter than mother-daughter relationship, parental tolerance of cross-gender behavior, and a mother who has been psychologically disturbed since the birth of her children. The heuristic value of this case will be discussed in relation to contemporary models of psychosexual development which emphasize the interaction of biological and psychosocial factors.

Prenatal diagnosis of congenital adrenal hyperplasia: reliability of amniotic fluid steroid analysis

The concentration of 170H-progesterone was measured in amniotic fluid samples collected from 55 mothers who had previously had a child with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. In eight pregnancies the levels of 170H-progesterone were raised; the parents elected to terminate in four and examinations of the fetus confirmed the diagnosis of congenital adrenal hyperplasia. In each case, the affected sib was a salt loser. The remaining four affected pregnancies proceeded to term and each infant had salt losing 21-hydroxylase deficiency. All 47 infants predicted to be unaffected were normal at birth. However, an increased plasma concentration of 170H-progesterone was documented in a male non-salt loser at three months of age. Prenatal diagnosis of congenital adrenal hyperplasia by amniotic fluid steroid analysis is reliable only for the salt losing variant of 21-hydroxylase deficiency. Of the affected sibs in this study, 20% died during infancy in a salt losing crisis. This simple and rapid prenatal test is sufficiently reliable to predict the group of infants most at risk in early infancy.

Fluorescence and chemiluminescence enzyme immunoassays of 17 alpha-hydroxyprogesterone in dried blood spotted on filter paper

Enzyme immunoassays for 17 alpha-hydroxyprogesterone (17-OHP) were developed. Horseradish peroxidase (HRP), glucose oxidase (GOD), invertase (INV) and glucose-6-phosphate dehydrogenase (G6PDH) were used as label enzymes. Double antibody coated beads or tubes were used for separating the bound and free fractions. Antisera used were prepared by using 4-carboxyethylthio-17-OHP and 3-carboxymethyl oxime-17-OHP-bovine serum albumin as immunogens. The bridge heterologous system was more sensitive than other site heterologous and homologous systems. The minimum amounts of 17-OHP detected were 0.25 and 1.0 pg/tube for fluorescence EIAs using HRP and GOD, and 0.1, 10 and 0.1 pg/tube for chemiluminescence EIAs using GOD, INV and G6PDH, respectively. The reproducibility and correlation with RIA were also studied. The present study demonstrates the feasibility of a neonatal screening for congenital adrenal hyperplasia.

Polymorphism of the human complement C4 and steroid 21-hydroxylase genes. Restriction fragment length polymorphisms revealing structural deletions, homoduplications, and size variants

Several autoimmune disorders as well as congenital adrenal hyperplasia (CAH) are either associated or closely linked with genetic variants of the fourth component of complement (C4A and C4B) and the enzyme steroid 21-hydroxylase (21-OH). These proteins are encoded by genes that are located downstream from the genes for complement proteins, C2 and factor B (BF) between HLA-B and -DR in the major histocompatibility complex (MHC). Previous studies of variants and null alleles were based on electrophoretic mobility of C4 protein and linkage with disease phenotypes. These data did not permit analysis of the basis for the observed null alleles and duplicated variants. We studied this region of the MHC in 126 haplotypes for a structural analysis of the four adjacent loci, C4A, 21-OHA, C4B, and 21-OHB. About half of the C4 genes typed as C4 null are deleted and several unrecognized homoduplicated C4 alleles were detected. Hence the frequencies of different C4 structural variants must be recalculated based on a direct analysis of the genes. Analysis of the C4/21-OH genes of patients with the classical (salt-wasting) form of CAH showed that some involve a deletion of the C4B and 21-OHB genes; whereas for two only the 21-OHB gene is deleted, i.e., the C4B gene is present. Together, these data provide a better understanding of the mechanisms generating and importance of deleted C4 and 21-OH null alleles in human disease.