Extensive clinical experience: nonclassical 21-hydroxylase deficiency

CONTEXT: Nonclassical congenital adrenal hyperplasia (CAH) owing to steroid 21-hydroxylase deficiency (NC21OHD) is the most frequent of all autosomal recessive genetic diseases, occurring in one in 100 persons in the heterogeneous New York City population. NC21OHD occurs with increased frequency in certain ethnic groups, such as Ashkenazi Jews, in whom one in 27 express the disease. NC21OHD is underdiagnosed in both male and female patients with hyperandrogenic symptoms because hormonal abnormalities in NC21OHD are only mild to moderate, not severe as in the classical form of CAH. Unlike classical CAH, NC21OHD is not associated with ambiguous genitalia of the newborn female. MAIN OUTCOME MEASURES: The hyperandrogenic symptoms include advanced bone age, early pubic hair, precocious puberty, tall stature, and early arrest of growth in children; infertility, cystic acne, and short stature in both adult males and females; hirsutism, frontal balding, polycystic ovaries, and irregular menstrual periods in females; and testicular adrenal rest tissue in males. CONCLUSIONS: The signs and symptoms of hyperandrogenism are reversed with dexamethasone treatment.     

非经典型21羟化酶缺陷症的研究进展

非经典型21羟化酶缺陷症是21羟化酶缺陷症中酶活性下降较轻的一种类型。其临床表现缺乏特异性，往往仅有轻度雄激素过多症状和体征；常混杂于高雄激素血症的其他病因中，与多囊卵巢综合征的临床特征相近，易于漏诊或误诊。因其发病率高，且常合并胰岛素抵抗及其他代谢紊乱，正日益受到人们重视。本文着重从其临床特征、分子遗传学特点、诊断与治疗等方面进行系统地阐述。     

Molecular pathology of 21-hydroxylase deficiency

Summary Steroid 21-hydroxylase deficiency is a recessively inherited disorder of adrenal steroidogenesis. Different clinical variants map to a single geneCYP21B, which maps within the HLA complex and is located about 30 kb proximal to a very closely related 21-hydroxylase pseudogene,CYP21A. The two CYP21 genes are located on highly homologous tandemly repeated 30 kb units, facilitating interlocus sequence exchanges. One type of exchange, unequal crossover, can result inCYP21B gene deletion or replacement of a large segment of theCYP21B gene by the analogous segment of theCYP21A gene. Gene conversion-like mechanisms can result in replacement of a very small segment ofCYP21B by the analogousCYP21A sequence, thereby introducing a deleteriousCYP21A-specific mutation. The vast majority of point mutation alleles seem to be accounted for by only a few of the mutations copied fromCYP21A and can be assayed by ASO hybridization or allele-specific amplification assays of selectively amplifiedCYP21B gene sequences. Genotype-phenotype correlations are largely as expected: mutations resulting in no or severely curtailed gene expression are associated with severe clinical phenotypes; those resulting in significant residual enzyme activity are associated with milder clinical phenotypes.     

非经典型21-羟化酶缺陷症的诊治

先天性肾上腺皮质增生症(congenital adrenal hyperpla-sia,CAH)是由基因突变导致肾上腺皮质激素生物合成过程中必需酶缺陷从而使肾上腺皮质类固醇激素合成障碍引起的一组疾病[1]。其中21-羟化酶缺陷症(21hydroxylasedeficiency,21-OHD)占90%~95%。作为单基因突变所致的常染色体隐性遗传疾病,经典型的21-OHD通常会在出生后即表现为恶心、呕吐、脱水、休克等肾上腺皮质激素缺乏的失盐表现。1958年,Jayle等[2]首次报道了21-OHD引起女性青春期后的高雄激素血症,此后多种诊断名词,包括晚发的、青春期后的、轻度的或者获得性的21-OHD,先后…     

Adult-onset familial adrenal 21-hydroxylase deficiency

Two sisters (28 and 30 years) were investigated for primary infertility and mild hirsutism. Both had normal puberty, were having regular menses and had normal female sexual characteristics. Studies revealed elevated urinary 17-ketosteroid levels (15.8, 18.8 mg/24 hours) and increased serum levels of 17-OH-progesterone (2,756, 1,121 ng/dl), 21-desoxycortisol (1,882, 1,090 ng/dl), progesterone (300, 346 ng/dl), dehydroepiandrosterone (DHA) (1,600, 1,700 ng/dl), androstenedione (402, 366 ng/dl) and testosterone (100, 104 ng/dl), together with a slight increase in serum 11-desoxycortisol (1,180, 1,560 ng/dl). Blood pressure, serum sodium/potassium, plasma renin and serum aldosterone, corticosterone, 11-desoxycorticosterone and cortisol levels were normal. The administration of ACTH caused a further increase in 21-hydroxylase precursors; the administration of dexamethasone normalized hormone levels and produced ovulatory cycles. Similar studies in two siblings were normal. The affected sisters were HLA identical and did not share any HLA antigens with their healthy siblings. The data suggest that these patients have a mild form of 21-hydroxylase deficiency which was insufficient to cause prenatal virilization. The gene for this disorder may be allelic with that for typical congenital adrenal hyperplasia.     

Steroid 21-hydroxylase deficiency in mice

The enzyme steroid 21-hydroxylase (21-OHase) plays a key role in adrenal steroidogenesis. Defects in this enzyme are responsible for one of the most common inborn errors of metabolism in humans. Duplicated genes for the enzyme are located in the class III region of the major histocompatibility complex (MHC), HLA. In the mouse, the genes encoding 21-OHase have been mapped to the homologous region of the H-2 complex. We previously described an H-2 recombinant haplotype aw18, in which the gene for the complement component C4 and one of the two genes for 21-OHase in the H-2 class III region have been deleted. We now report that newborn aw18 homozygous mice are deficient in 21-OHase activity, and that homozygosity for the aw18 haplotype directly causes death at the early postnatal stage. Morphological changes in the adrenal glands of newborn aw18 homozygotes are also observed. The aw18 recombinant haplotype is expected to serve as a useful and, thus far, unique experimental system to study adrenal steroidogenesis in vivo and as an animal model for the inherited human disease of congenital adrenal hyperplasia.     

Clinical heterogeneity of 21-hydroxylase deficiency of sibs with identical 21-hydroxylase genes.

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is a disorder with different clinical manifestations, that results from mutations in the P-450(c21) gene. Direct sequence analysis of P-450(c21) genes in a family demonstrates that patients with different clinical forms of congenital adrenal hyperplasia can have identical P-450(c21) genes, suggesting that other effects play a role in developing the different clinical forms.     

Phenotypic evolution of classic 21-hydroxylase deficiency

We describe a female patient who was diagnosed and treated at birth for a classic form of salt-losing congenital adrenal hyperplasia. At 17 years of age, against medical advice, she discontinued both mineralocorticoid and glucocorticoid replacement with no resulting clinical symptoms other than the occurrence of amenorrhoea. Steroid metabolites revealed significant abnormalities of the renin-angiotensin-aldosterone axis, as well as of pituitary-adrenal function. Analysis of our patient's DNA showed only one deleterious CYP21 mutation, an intron 2 base pair change activating a cryptic splice site. We speculate that expression of this patlent's CYP21 genes may be altered by the effects of ageing or by changes in the steroid milieu.     

Genetics of adrenal steroid 21-hydroxylase deficiency

Impairment of 21-hydroxylation is the most common enzymatic deficiency resulting in the syndrome of CAH, which may present either in the classical form in infants or in the nonclassical form in older individuals. Variable signs and symptoms of androgen excess are common to both types of the disorder, which are transmitted as autosomal recessive traits linked to HLA. Virilization begins in the second month of gestational life in classical 21-OHD, but postnatally in the nonclassical form. Salt wasting is a feature of the disease in a large number of classical patients; in the simple virilizing form aldosterone biosynthesis, a function of the adrenal zona glomerulosa, is intact. Additionally, no patient with nonclassical 21-OHD has been found to have salt wasting. Levels of precursor hormones are less markedly elevated in nonclassical 21-OHD, reflecting a less severe enzyme deficiency; coordinates of basal and stimulated 17-OHP are plotted on a nomogram to ascertain diagnostic category within a family. Confirmatory evidence of heterozygosity within the family of an affected proband is found by performing HLA typing. Specific linkage disequilibria exist for the classical and nonclassical forms of 21-OHD. Frequency of the classical disease is 1/5,000-1/15,000 in Caucasians, whereas the nonclassical disease is found in approximately 1/100 individuals in the Caucasian population, placing the latter disorder among the most common autosomal recessive disorders in man. A deletion of the active 21-hydroxylase gene has been detected in some classical patients; further investigations are in progress to elucidate the molecular genetics of this disease.     

21-羟化酶缺陷型先天性肾上腺皮质增生症治疗现状

21-羟化酶缺陷型先天性肾上腺皮质增生症是一类常见的人类常染色体隐性遗传病.患儿可具有失盐、脱水、两性畸形、假性性甲熟及肾上腺危象等临床征象,如何治疗该病一直为学者们所关注.近年来,在产前及出生后药物治疗领域,一些新兴药物及治疗方案在减轻患儿代谢紊乱,改善患儿身高等方面显示出了良好疗效.此外,针对该遗传性疾病的基因治疗...     

Haplotypes of the steroid 21-hydroxylase gene region encoding mild steroid 21-hydroxylase deficiency.

Haplotypes of the complement 4 (C4) and steroid 21-hydroxylase [21-OHase; steroid hydrogen-donor: oxygen oxidoreductase (21-hydroxylating), EC 1.14.99.10] repeated gene complex were studied in nine families with at least one member affected with a mild form of 21-OHase deficiency. DNA probes from different parts of the repeated C4/21-OHase unit were used to follow the segregation of hybridization patterns in the families. Ten structurally distinct haplotypes of the C4/21-OHase gene region were identified, and the encoded phenotype was assigned to 34 of the 36 C4/21-OHase haplotypes. Four structurally different haplotypes with three C4/21-OHase repeat units were found. Eight of the nine haplotypes found with triplications of the C4/21-OHase repeat unit encoded the mild form of 21-OHase deficiency, whereas one particular triplicated haplotype encoded a severe form of the disease. In one case the mild form of 21-OHase deficiency was encoded by a haplotype with a single C4/21-OHase repeat unit. Mild 21-OHase deficiency was predicted in a patient by the presence of a triplicated haplotype. The finding of deranged 21-OHase genes on all triplicated C4/21-OHase haplotypes indicate that most of these common haplotypes carry mutated 21-OHase genes, and thus may cause functional polymorphism of general importance in the population.     

非经典型21-羟化酶缺乏症基因型和临床特征

目的　对中国人非经典型 21 羟化酶缺乏症(21 OHD)基因型进行研究。方法　8例非经典型 21 OHD患者, 35例经典型 21 OHD患者,及 20例正常对照者基因组DNA用特定引物扩增CYP21的两个片段,片段 1从外显子 1→外显子 3,片段 2从外显子 3→外显子 10。用片段 1和片段 2为模板进行第二轮PCR,用特定限制性内切酶消化后经琼脂糖凝胶电泳鉴定突变。结果　 ( 1 ) 8例中国人非经典型 21 OHD最常见的突变为P30L(6 /16, 37. 5% ),其次为V281L(4 /16, 25. 0% ), 引起 21 羟化酶活性中、重度下降的突变i2g(3 /16, 18. 8% ),Q318X和R356W各 (1 /16, 6. 3% ),I172N(3 /16, 18. 8% )。(2)非经典型21 OHD患者ACTH1 24兴奋试验 17 OH孕酮基础值为 (23. 9±28. 4)μg/L,兴奋后为 ( 92. 0±83. 7 )μg/L。(3)基因型分型与 21 OHD的临床表型有明显的相关性。结论　(1)中国人非经典型 21 OHD最常见的突变是P30L,其次为V281L,不同于白种人。(2)对高雄激素血症患者要注意非经典型 21 OHD的诊断和筛查。     

Detection of heterozygous carriers for 21-hydroxylase deficiency by plasma 21-deoxycortisol measurement

Using a highly specific radioimmunoassay recently described, plasma 21-deoxycortisol levels were measured in 55 heterozygous carriers of 21-hydroxylase deficiency (as demonstrated by HLA typing). Mean baseline 21-deoxycortisol levels were above the normal range, but there was a 38% overlap with control values. In contrast to 17-hydroxyprogesterone levels, which in 71% of the subjects remained within the normal range one hour after ACTH stimulation, 21-deoxycortisol levels increased over stimulated control levels in all but two heterozygous carriers. No differences as to the levels were observed between heterozygous carriers for the classic and the late-onset forms. Plasma 21-deoxycortisol measurement appears to be a valid tool in the biological detection of heterozygosity for 21-hydroxylase deficiency and its implications in genetic counselling.     

CYP21A2 intronic variants causing 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder mainly caused by defects in the steroid 21-hydroxylase gene (CYP21A2). Most of CYP21A2 mutations result from intergenic recombinations between CYP21A2 and closely linked CYP21A1P pseudogene. Rare mutations not generated by gene conversion account for 5–10% of 21-hydroxylase deficiency alleles. Intronic variants represent only a little part of these but their effect on the protein is generally deleterious. The aim of this paper is to provide a comprehensive literary review regarding all intronic CYP21A2 pathological variants reported to date. In addition, we describe three novel causing disease variants in our patients affected by the classic form of CAH: IVS4-1G > A, IVS5-8 T > A, IVS8-2A > G. In silico analysis revealed that all these substitutions affect the splicing process leading to a non-functional protein. Based on these results, we are able to classify them as pathological variants according to the patient's phenotype.     

Analysis of mutations causing steroid 21-hydroxylase deficiency

Steroid 21-hydroxylase deficiency is the most frequent cause of congenital adrenal hyperplasia, an inherited inability to synthesize cortisol. Mutations causing this disorder have been characterized by hybridization analysis of patient DNA samples using cDNA and oligonucleotide probes, and by cloning and sequencing of mutant 21-hydroxylase (CYP21B) genes. About 20% of mutant alleles carry a 30 kilobasepair deletion that includes the 3' end of the CYP21A pseudogene, the C4B complement gene, and the 5' end of CYP21B, leaving behind a single CYP21A-like gene that is not functional. Non-deletional mutations include a nonsense mutation at codon 318 that is associated with severe disease and missense mutations at codons 172 (isoleucine to asparagine) and 281 (valine to leucine) that are respectively associated with intermediate and mild deficiency states. All of these alleles have apparently resulted from gene conversion events that have transferred deleterious mutations from the CYP21A pseudogene to CYP21B. Thus, recombinations between CYP21A and CYP21B probably account for the majority of 21-hydroxylase deficiency alleles.     

糖皮质激素替代治疗对21-羟化酶缺陷症患者糖脂代谢的影响

目的 单纯男性化型和非经典型21-羟化酶缺陷症(21-OHD)患者常常合并糖脂代谢异常,本文研究接受糖皮质激素替代治疗的21-OHD患者的糖脂代谢的变化.方法 收集2004年至2010年期间接受糖皮质激素治疗的21-OHD患者32例,同时收集到未接受糖皮质激素治疗的新诊断的21-OHD患者31例,均经21-羟化酶(CYP21)基因测序突变分析证实为CYP21 A2基因突变.检测人体测量学指标和空腹血糖、血脂、胰岛素、性激素水平,以及口服葡萄糖耐量试验(OGTT)和胰岛素释放试验.结果 糖皮质激素治疗组睾酮[(0.61±0.12对4.10±0.66)ng/ml,P＜0.01]、17-羟孕酮[17-OHP,(14.83±3.48对48.52±4.72) ng/ml,P＜0.01]、硫酸脱氢表雄酮[DHEAS,(55.7±23.6对405.2±65.7)μg/dl,P＜0.01]、促肾上腺皮质激素[ ACTH,(105.8±44.7对617.4± 163.3)pg/ml,P＜0.01]水平明显下降,而体重指数[(23.2±0.9对21.1±0.5)kg/m2,P＜0.05]、收缩压[(120.5±1.3对115.5±1.8)mm Hg,P＜0.05,1mm Hg=0.133 kPa]和甘油三酯[(1.8±0.2对1.1±0.1)mmol/L,P＜0.05]却明显增高,并且糖皮质治疗组的稳态模型评估的胰岛素抵抗指数(HOMA-IR)也明显高于未治疗组[(2.07±0.27对1.16±0.12),P＜0.01].多因素回归分析表明体重指数与HOMA-IR的相关性最强.结论 糖皮质激素治疗增加21-OHD患者体重指数、血清甘油三酯水平、收缩压和降低胰岛素敏感性.其中体重指数增加是导致胰岛素抵抗的主要原因,因此21-OHD患者的糖皮质激素治疗需注意代谢紊乱问题.     

Comparative study of prednisolone versus hydrocortisone acetate for treatment of patients with the classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Hydrocortisone acetate is usually employed in the treatment of classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. In Brazil, however, oral hydrocortisone acetate is only available from manipulation pharmacies. Prednisolone has stable oral pharmaceutical formulations commercially available, with the advantage of a single daily dose. The aim of this study was to compare the efficacy of oral prednisolone and oral hydrocortisone in the treatment of CAH due to 21-hydroxylase deficiency. Fifteen patients with mean (SD) chronological age of 7.2 (3.6) years, were evaluated in two consecutive 1-year periods. In the first year, hydrocortisone (17.5 mg/m2/day, divided in three doses) was used in the treatment, followed by the use of prednisolone (3 mg/m2/day, once in the morning) in the second year. The comparison between the two treatments was assessed after a one-year treatment period by: variation of height standard deviation score (SDS) (delta Height SDS), variation of height SDS according to bone age (delta BA SDS), variation of body mass SDS (delta BMI SDS) and serum levels of androstenedione. No significant difference was observed in relation to the delta Height SDS, delta BA SDS and delta BMI SDS. No significant difference was observed in the serum levels of androstenedione. We conclude that the efficacy of prednisolone administered once a day orally is comparable to the oral use of hydrocortisone three times a day. Oral prednisolone may be an option for patients with CAH due to 21-hydroxylase deficiency.