Congenital adrenal hyperplasia due to point mutations in the type II 3 beta-hydroxysteroid dehydrogenase gene.

Classical 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta-HSD) deficiency is an autosomal recessive form of congenital adrenal hyperplasia characterized by a severe impairment of steroid biosynthesis in both the adrenals and the gonads. We describe the nucleotide sequence of the two highly homologous genes encoding 3 beta-HSD isoenzymes in three classic 3 beta-HSD deficient patients belonging to two apparently unrelated pedigrees. No mutation was detected in the type I 3 beta-HSD gene, which is mainly expressed in the placenta and peripheral tissues. Both nonsense and frameshift mutations, however, were found in the type II 3 beta-HSD gene, which is the predominant 3 beta-HSD gene expressed in the adrenals and gonads, thus providing the first elucidation of the molecular basis of this disorder.

Decrease of anti-Mullerian hormone in genetic spermatogenic failure.

The aim of this study was to compare anti-Mullerian hormone (AMH) plasma levels in patients with azoospermia according to the physiopathology. In a prospective clinical study from April 2008 to March 2009 in University Hospital, we measured AMH levels in 49 consecutive patients with azoospermia. AMH plasma levels were correlated with FSH, inhibin B, bioavailable testosterone plasma levels and testicular volume and compared between nonobstructive azoospermia (NOA) and obstructive azoospermia (OA) and within four physiopathological subgroups of NOA: genetic, cryptorchidism, cytotoxic and unexplained. AMH, FSH, inhibin B, bioavailable testosterone plasma levels and testicular volumes were all related to each other. AMH plasma levels were lower in NOA relatively to OA. Lowest values were observed in cases of genetic NOA and on the other hand, the values observed in case of cytotoxic NOA were as high as the values observed in OA. FSH, inhibin B, bioavailable testosterone and testicular volume were not different between genetic and cytotoxic NOA. These results suggest that the decrease in AMH plasma levels is related to the origin of NOA, with low values in genetic NOA and values similar to OA in cytotoxic NOA. Further studies will be useful to understand the fine regulation of AMH production.

[Hypoplasia adrenal congenita of anencephalic type: two cases with pituitary abnormalities and review of literature]. / L'hypoplasie surrénale congénitale de type anencéphalique: deux cas avec anomalies hypophysaires, sans mutation de DAX-1 et SF-1 et revue de la littérature.

Hypoplasia adrenal congenita is an extremely uncommon disease of early onset. This condition can be lethal in the absence of treatment. Some forms are due to the congenital adrenal hypoplasia of anencephalic type whose origin is even unknown. Here, we present two cases of congenital adrenal hypoplasia of anencephalic type with pituitary abnormalities. The two male newborns died because adrenal insufficiency in the neonatal period. The adrenal glands were hypoplastic with a histological structure of anencephalic type Immunocytochemical study of the pituitary revealed an absence of the gonadotrophs. No mutation of DAX 1 and SF-1 was found.

Only two mutations detected in 15 Tunisian patients with 11ß-hydroxylase deficiency: the p.Q356X and the novel p.G379V.

Steroid 11ß-hydroxylase deficiency is the second most common cause of congenital adrenal hyperplasia, resulting in virilization, glucocorticoid deficiency and hypertension. The 11ß-hydroxylase enzyme is encoded by the CYP11B1 gene and mutations in this gene are responsible for this disease. The aim of this study was to characterize mutations in the CYP11B1 gene and to determine their frequencies in a cohort of Tunisian patients. The molecular genetic analysis was performed by direct nucleotide sequencing of the CYP11B1 gene in 15 unrelated Tunisian patients suffering from classical 11ß-hydroxylase deficiency. Only two mutations were detected in homozygous state in the CYP11B1 gene of all patients, the p.Q356X in exon 6 (26.6%) and the novel p.G379V in exon 7 with large prevalence (73.3%). This is the first report of screening for mutations of CYP11B1 gene in the Tunisian population and even in the Arab population.

Bilateral adrenalectomy for severe hypertension in congenital adrenal hyperplasia due to 11beta-hydroxylase deficiency: long term follow-up.

CONTEXT: Bilateral adrenalectomy has been recently proposed as a surgical treatment option for patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. There is however little documented data about the long-term efficiency and potential side effects of this treatment. Patients with 11beta-hydroxylase deficiency (11betaHD) have been also concerned by this new approach. OBJECTIVE: Our objective was to describe our experience with bilateral adrenalectomy as a treatment of severe hypertension in a patient with 11betaHD deficiency and to report the long term follow-up (72 months) results after surgery. PATIENT AND INTERVENTION: A 22-year-old genetically female patient with 11betaHD deficiency was raised as a male because of severe pseudohermaphroditism. The patient has been managed by conventional steroid suppressive therapy and antihypertensive drugs with limited success; hypertension remained uncontrolled and led to severe complications. Bilateral adrenalectomy was offered to him. RESULTS: The intervention was followed by immediate blood pressure normalization and resulted in remarkable clinical improvement. Good compliance with glucocorticoid and androgen substitutive therapies was noted. However, a high 11-deoxycortisol, presumably due to non-ovarian ectopic adrenal rests was noted 24 months after surgery. CONCLUSION: Bilateral adrenalectomy is a safe and efficient method of managing CAH with selected patients. Long-term clinical and biochemical follow-up of patients with CAH treated by bilateral adrenalectomy is needed to earlier detect ectopic adrenal rests.

p.H62L, a rare mutation of the CYP21 gene identified in two forms of 21-hydroxylase deficiency.

CONTEXT: Steroid 21-hydroxylase deficiency is the most common enzymatic defect causing congenital adrenal hyperplasia with good genotype/phenotype relationships for common mutations. To determine the severity of rare mutations is essential for genetic counseling and better understanding of the structure-function of the cytochrome P450c21. OBJECTIVE: The p.H62L mutation was the most frequent of 60 new mutations detected in 2900 steroid 21-hydroxylase deficiency patients, either isolated or associated on the same allele with a mild mutation (p.P453S, p.P30L, or partial promoter). Because phenotypes seemed to differ between patients with isolated or associated p.H62L, a detailed phenotype description and functional studies were performed. RESULTS: Regarding phenotype, patients with isolated p.H62L had a nonclassical form, whereas patients with the association p.H62L + mild mutation had a simple virilizing form. Functional studies showed that p.H62L reduced the conversion of the two substrates, progesterone and 17-hydroxyprogesterone, in the same way as the mild p.P453S; the association p.H62L + p.P453S decreased enzymatic activity more strongly while conserving residual activity at a level intermediate between p.P453S and p.I172N. This suggested that p.H62L was a mild mutation, whereas a synergistic effect occurred when it was associated. Analysis of p.H62L in a three-dimensional model structure of the CYP21 protein explained the observed in vitro effects, the H62 being located in a domain implied in membrane anchoring. CONCLUSION: According to phenotype and functional studies, p.H62L is a mild mutation, responsible for a more severe phenotype when associated with another mild mutation. These data are important for patient management and genetic counseling.

[Gayet-Wernicke's encephalopathy. A study of 13 cases observed in a refugee population hospitalized at the Conakry Teaching Hospital]. / Encéphalopathie de Gayet-Wernicke. Etude de 13 observations dans une population de patients réfugiés hospitalisés pour affections neurologiques au CHU de Conakry.

The authors report 13 cases of Gayet-Wernicke's encephalopathy observed in 13 patients of a refugee population. 11 presented the classical triad: oculomotor signs, cerebral ataxia and state of confusion and in 2 patients, only 2 symptoms were noted. The etiological factors: chronic alcoholism, malnutrition, uncontrollable vomiting, HIV and tuberculosis were identified. The outcome was evaluated on the basis of the disappearance of symptoms after treatment with 500 mg of thiamine in 7 patients, 1 death and 5 patients progressed toward Korsakoff amnesic syndrome.

Rearrangements and point mutations of P450c21 genes are distinguished by five restriction endonuclease haplotypes identified by a new probing strategy in 57 families with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is caused by disorders of the P450c21B gene, which, with the P450c21A pseudogene, lies in the HLA locus on chromosome 6. The near identity of nucleotide sequences and endonuclease cleavage sites in these A and B loci makes genetic analysis of this disease difficult. We used a genomic DNA probe that detects the P450c21 genes (A pseudogene, 3.2 kb; B gene, 3.7 kb in Taq I digests) and the 3' flanking DNA not detected with cDNA probes (A pseudogene, 2.4 kb; B gene, 2.5 kb) to examine Southern blots of genomic DNA from 68 patients and 165 unaffected family members in 57 families with CAH. Of 116 CAH-bearing chromosomes, 114 could be sorted into five easily distinguished haplotypes based on blots of DNA digested with Taq I and Bgl II. Haplotype I (76 of 116, 65.6%) was indistinguishable from normal and therefore bore very small lesions, presumably point mutations. Haplotype II (4 of 116, 3.4%) and haplotype III (8 of 116, 6.9%) had deletions and duplications of the P450c21A pseudogene but had structurally intact P450c21B genes presumably bearing point mutations; point mutation thus was the genetic defect in 88 of 116 chromosomes (75.9%). Haplotypes IV and V lack the 3.7-kb Taq I band normally associated with the P450c21B gene. Haplotype IV (13 of 116, 11.2%) retains all other bands, indicating that the P450c21B gene has undergone a gene conversion event, so that it is now also associated with a 3.2-kb band. Haplotype V (13 of 116, 11.2%) lacks the 2.4-kb Taq I fragment and the 12-kb Bgl II fragments normally associated with the P450c21A pseudogene, as well as lacking the 3.7-kb Taq I fragment, indicating deletion of approximately 30 kb of DNA, resulting in a single hybrid P450c21A/B gene. Most (114 of 116, 98%) CAH alleles thus can easily be classified with this new probing strategy, eliminating many ambiguities resulting from probing with cDNA.

An autoregulatory loop controlling CYP1A1 gene expression: role of H(2)O(2) and NFI.

Cytochrome P450 1A1 (CYP1A1), like many monooxygenases, can produce reactive oxygen species during its catalytic cycle. Apart from the well-characterized xenobiotic-elicited induction, the regulatory mechanisms involved in the control of the steady-state activity of CYP1A1 have not been elucidated. We show here that reactive oxygen species generated from the activity of CYP1A1 limit the levels of induced CYP1A1 mRNAs. The mechanism involves the repression of the CYP1A1 gene promoter activity in a negative-feedback autoregulatory loop. Indeed, increasing the CYP1A1 activity by transfecting CYP1A1 expression vectors into hepatoma cells elicited an oxidative stress and led to the repression of a reporter gene driven by the CYP1A1 gene promoter. This negative autoregulation is abolished by ellipticine (an inhibitor of CYP1A1) and by catalase (which catalyzes H(2)O(2) catabolism), thus implying that H(2)O(2) is an intermediate. Down-regulation is also abolished by the mutation of the proximal nuclear factor I (NFI) site in the promoter. The transactivating domain of NFI/CTF was found to act in synergy with the arylhydrocarbon receptor pathway during the induction of CYP1A1 by 2,3,7,8-tetrachloro-p-dibenzodioxin. Using an NFI/CTF-Gal4 fusion, we show that NFI/CTF transactivating function is decreased by a high activity of CYP1A1. This regulation is also abolished by catalase or ellipticine. Consistently, the transactivating function of NFI/CTF is repressed in cells treated with H(2)O(2), a novel finding indicating that the transactivating domain of a transcription factor can be targeted by oxidative stress. In conclusion, an autoregulatory loop leads to the fine tuning of the CYP1A1 gene expression through the down-regulation of NFI activity by CYP1A1-based H(2)O(2) production. This mechanism allows a limitation of the potentially toxic CYP1A1 activity within the cell.

[Clinical and tomographic aspects of 29 cases of phakomatosis in Guinea]. / Aspects clinique et scannographique de 29 observations de phacomatoses en Guinée.

The purpose of this report is to describe 29 cases of phakomatosis including 18 cases of tuberous sclerosis (Bourneville) and 11 cases of neurofibromatosis (von Recklinghausen) observed over a 10-year period at the Neurology Department of the University Hospital Centre in Conakry, Guinea. Findings during this period were consistent with those classically reported in the literature: high frequency of advanced skin lesions coalescing into massive tumours, occurrence of seizures of all types and development of a wide variety of complications as a result of late diagnosis. Our experience underscores the need for follow-up and surveillance of these patients by somatic studies based on neurological, ophthalmologic and tomographic data depending on clinical findings.

Morphofunctional modifications associated with the inhibition by estradiol of MtTF4 rat pituitary tumor growth.

The MtTF4 pituitary tumor has been induced in Fischer rats by chronic estrogen administration. Recently, we reported that sustained pharmacological treatment of Fischer rats with 17 beta-estradiol inhibited the growth of the MtTF4 tumor transplanted s.c. The present work describes the associated morphofunctional changes occurring in the tumor during 17 beta-estradiol inhibition. It is shown that a 7-day 17 beta-estradiol treatment resulted in an increase of the surface area of cells, nuclei, nucleoli, Golgi complexes, and rough endoplasmic reticulum and an increase in the number of euchromatin-rich nuclei. Flow cytometry analysis of DNA distribution suggested that estradiol affects the cell progression through the early S phase. The ratio of RNA to DNA increased significantly, reflecting cell hypertrophy. Moreover, there was a significant increase in tumor prolactin concentration and a marked enhancement in the intensity of the immunocyto-chemical reaction with rat prolactin antiserum. On the other hand, cell mitoses were dramatically decreased. These morphofunctional changes indicate that the inhibition of the tumor growth by estradiol is accompanied by an evolution of the tumor cell population towards a more differentiated state. However, it cannot be decided whether 17 beta-estradiol induces a shift from a proliferative state to a differentiated state or whether 17 beta-estradiol treatment results in a selection of a subpopulation of tumor cells that are slow growing and more differentiated.

Endocrine and molecular investigations in a cohort of 25 adolescent males with prominent/persistent pubertal gynecomastia.

Pubertal gynecomastia is a common condition observed in up to 65% of adolescent males. It is usually idiopathic and tends to regress within 1-2 years. In this descriptive cross-sectional study, we investigated 25 adolescent males with prominent (>B3) and/or persistent (>2 years) pubertal gynecomastia (P/PPG) to determine whether a hormonal/genetic defect might underline this condition. Endocrine investigation revealed the absence of hormonal disturbance for 18 boys (72%). Three patients presented Klinefelter syndrome and three a partial androgen insensitivity syndrome (PAIS) as a result of p.Ala646Asp and p.Ala45Gly mutations of the androgen receptor gene. The last patient showed a 17α-hydroxylase/17,20-lyase deficiency as a result of a compound heterozygous mutation of the CYP17A1 gene leading to p.Pro35Thr(P35T) and p.Arg239Stop(R239X) in the P450c17 protein. Enzymatic activity was analyzed: the mutant protein bearing the premature stop codon R239X showed a complete loss of 17α-hydroxylase and 17,20-lyase activity. The mutant P35T seemed to retain 15-20% of 17α-hydroxylase and about 8-10% of 17,20-lyase activity. This work demonstrates that P/PPG had an endocrine/genetic cause in 28% of our cases. PAIS may be expressed only by isolated gynecomastia as well as by 17α-hydroxylase/17,20-lyase deficiency. Isolated P/PPG is not always a 'physiological' condition and should thus be investigated through adequate endocrine and genetic investigations, even though larger studies are needed to better determine the real prevalence of genetic defects in such patients.

Prenatal treatment of congenital adrenal hyperplasia.

Prenatal diagnosis of congenital adrenal hyperplasia (CAH) is accurate and prenatal therapy is effective in significantly reducing or even eliminating virilization of females affected by CAH, sparing these children the consequences of genital surgery, sex missassignment and gender confusion. However, both the physical and psychological development of these children and the possibility of long-range adverse effects in the mothers need to be evaluated further. Prospective multicentre studies covering several decades are being designed.

[Adrenal hypoplasia congenita: four new cases in children]. / Hypoplasie congénitale des surrénales : à propos de quatre observations.

Adrenal hypoplasia congenita (AHC) is an extremely uncommon disease of early onset. This condition can be lethal in the absence of adapted treatment. Some of these diseases are related to changes in the gene DAX1 that encodes a member of the superfamily of hormone nuclear receptors. It is a transcriptional repressor that is central in the morphogenesis of the adrenals and the gonadic differentiation. Here we report on four cases of X- linked AHC. In the first two familial cases, mutations were identified and mothers were heterozygotes. Abnormally low levels of estriol were evidenced during the pregnancy leading to an early diagnosis and adapted care of the affected male neonates. These children are doing well with a 21-and 20 months follow-up with hormone replacement at the present time. The two last cases corresponded to a contiguous gene syndrome associating AHC to glycerol-kinase deficiency that was revealed respectively at six days and seven years of age by acute adrenal insufficiency.

[Development of the human adrenal glands]. / Le développement de la surrénale humaine.

The human adrenal is an endocrine gland located at the superior part of the kidney. Composed of the adrenal cortex of mesoblastic origin and the adrenal medulla of neuroectoblastic origin, the human fetal adrenal grows considerably during the first three months of development. From 12 to 18 weeks of development (WD), the weight of the adrenals increases seven-fold. The gland's weight doubles from 18 to 28 WD and from 28 to 36 WD. At birth, the two adrenals weigh on average 10 g. At the 8th week, two zones are individualized in the adrenal cortex: the definitive zone and the fetal inner zone. At the second trimester, according to ultrastructural and biochemical studies, a third zone, called the transition zone, is individualized between the definitive zone and the fetal inner zone. The definitive zone persists, but the origin of the three zones (glomerular, fascicular and reticular) of adult adrenal cortex is not known. The fetal inner zone regresses from the 5th month of gestation and disappears totally one year after birth. At the 8th week, the immature neuroblasts migrate to the definitive zone, then to the fetal inner zone to compose the adrenal medulla, which develops essentially after birth and during the first year. Before the 10th week, the human fetal adrenal is able to produce steroid hormones, in particular dehydroepiandrosterone sulfate (DHEA-S); the secretion of cortisol remains discussed. The development of the human fetal adrenal is complex and is under the control of hormones (ACTH, LH and betaHCG), growth factors (ACTH essentially) and transcription factors (essentially SF1 and DAX-1). Knowledge of morphological and molecular phenomena of this development permits to understand the pathophisiology of congenital adrenal deficiencies.

21-Hydroxylase deficiency: an exemplary model of the contribution of molecular biology in the understanding and management of the disease.

Congenital adrenal hyperplasia (CAH) is a family of autosomal recessive disorders caused by mutations in genes encoding the enzymes involved in one of the various steps of adrenal steroid synthesis. Steroid 21-hydroxylase deficiency (21-OHD) is responsible for over 95% of the 5 forms of CAH, and results due to enzymatic defect owing to mutation in the CYP21 gene. The disease has two major clinical presentations. The "classical" form is severe, and divided into a salt wasting (SW) and simple virilizing (SV) subgroups. In both, affected female fetuses undergo virilization of the external genitalia prenatally and present at birth with sexual ambiguity. In addition, in both sexes infants with SW CAH are at risk of life-threatening adrenal crisis without treatment. This is why it is so important to make a diagnosis and to counsel the families. The diagnosis is easy by measuring the plasma levels of 17-hydroxyprogesterone (17-OHP) in antenatal (amniotic fluid), or perinatal samples (peripheral blood). Confirmation by molecular genetic analysis is advised. The second form of 21-OHD is called "non classical" because the presentation is much less severe and the onset of clinical expression occurs long after birth, often in the peripubertal period, as non-specific symptoms of hyperandrogeny. The unambiguous diagnosis of the latter requires a simple short ACTH test, with the measurement of 17-OHP at 60 min. In both forms, the mutations on the gene CYP21 responsible for the disease are now well known and can be identified by molecular biology techniques. There is a good correlation between phenotypes and genotypes, due to variable amount of the 21-hydroxylase-enzyme activity left (null to 50-60%). SW, SV and NC forms are associated with distinct mutations or combination of mutations. Nowadays, by combining hormonal and molecular tests, it is possible to predict the clinical form of the disease in a given family in the context of a prenatal diagnosis, which can lead to a prenatal treatment. Therefore, 21-OHD genotyping also appears essential for a new approach of genetic counseling, prediction of clinical form after postnatal screening and to define the post-ACTH 17-OHP values indicating the cut-off lines between NC, heterozygote and normal subjects.

[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.

Aerosol administration of a recombinant adenovirus expressing CFTR to cystic fibrosis patients: a phase I clinical trial.

Ad CFTR, a replication-deficient adenovirus expressing the human cystic fibrosis transmembrane conductance regulator (CFTR), was administered by aerosolization in a single escalating dose to three pairs (cohorts) of cystic fibrosis (CF) patients. Buffer only was administered to the nose and lungs 9-14 days before nasal instillation of virus followed the day after by aerosolization of Ad CFTR to the lung. Nasal doses (defined in terms of viral plaque forming units, pfu) were 10(5), 10(7), and 4 x 10(8), whereas aerosolized doses were 10(7), 10(8), 5.4 x 10(8) for each cohort, respectively. No acute toxic effects were observed in the first 4 weeks after virus treatment. Shedding of infectious Ad CFTR was never detected, whereas detection of vector DNA sequences and CFTR expression demonstrated DNA transfer to the nose and airways of patients. No significant deviations in immunological and inflammatory parameters were observed in serum and in bronchoalveolar lavage (BAL). Importantly, for all patients, the serum anti-adenovirus antibody levels did not change significantly from baseline and no antibodies against adenovirus were found in BAL.

How a patient homozygous for a 30-kb deletion of the C4-CYP 21 genomic region can have a nonclassic form of 21-hydroxylase deficiency.

A case of nonclassic (NC) 21-hydroxylase deficiency, with a moderately elevated 17-hydroxyprogesterone level (145 nmol/L in filter paper blood spot), was detected in newborn screening. The newborn's phenotype was female, with no sign of virilization. Confirmatory diagnosis revealed elevated serum levels of 17-hydroxyprogesterone and of 21-desoxycortisol, whereas cortisol, PRA, and electrolytes were normal. Hydrocortisone substitution was considered at the age of 6 months, when virilization became obvious. For clinical reasons, this case had to be classified as late-onset congenital adrenal hyperplasia (CAH) with unusually early manifestation. However, the diagnosis of classic 21-hydroxylase deficiency was obtained by Southern blotting studies, showing that she was homozygous for the 30-kb deletion, including the 3' end of CYP21P pseudogene, the C4B gene, and the 5' end of the functional CYP21 gene. Further studies, using PCR and sequencing, were conducted to explain the discrepancy between this genotype, usually associated with a classic salt-wasting form, and the girl's phenotype. Typically, patients homozygous for the 30-kb deletion encoding classic CAH possess a unique CYP21P/21 hybrid gene with the junction site located after the third exon, yielding a nonfunctional pseudogene. The girl in question, however, was heterozygous for the 8-bp deletion, suggesting that the chimeric pseudogene on one allele had a junction site before the third exon. She was compound heterozygous for a 30-kb deletion encoding classic CAH on the paternal allele, and a 30-kb deletion encoding NC CAH on the maternal allele. This novel maternal CYP21P/21 hybrid gene is characterized by a junction site before intron 2 and differs from the normal CYP21 gene only by the P30L mutation in exon 1 and the promoter region of the CYP21P pseudogene. Because the P30L mutation has been described to result in an enzyme with 30-60% activity of the normal P450c21 enzyme, and the CYP21P promoter reduced the transcription to 20% of normal, this puzzling phenotype of a NC CAH with early onset may be fully explained by the genotype of the patient and considered as an intermediate form between the simple virilizing and NC form.

Deletion hybrid genes, due to unequal crossing over between CYP11B1 (11beta-hydroxylase) and CYP11B2(aldosterone synthase) cause steroid 11beta-hydroxylase deficiency and congenital adrenal hyperplasia.

Chromosomal rearrangements are natural experiments that can provide unique insights into in vivo regulation of genes and physiological systems. We have studied a patient with congenital adrenal hyperplasia and steroid 11beta-hydroxylase deficiency who was homozygous for a deletion of the CYP11B1 and CYP11B2 genes normally required for cortisol and aldosterone synthesis, respectively. The genes were deleted by unequal recombination between the tandemly arranged CYP11B genes during a previous meiosis, leaving a single hybrid gene consisting of the promoter and exons 1-6 of CYP11B2 and exons 7-9 of CYP11B1. The hybrid gene also carried an I339T mutation formed by intracodon recombination at the chromosomal breakpoint. The mutant complementary DNA corresponding to this gene was expressed in COS-1 cells and was found to have relatively unimpaired 11beta-hydroxylase and aldosterone synthase activities. Apparently the 11beta-hydroxylase deficiency and the adrenal hyperplasia are due to the lack of expression of this gene in the adrenal zona fasciculata/reticularis resulting from replacement of the CYP11B1 promoter and regulatory sequences by those of CYP11B2.