This Article Abstract Full Text (PDF) All Versions of this Article: 92/6/2318    most recent Author Manuscript (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Scott, R. R. Articles by Miller, W. L. Search for Related Content PubMed PubMed Citation Articles by Scott, R. R. Articles by Miller, W. L. Related Collections Adrenal and Hypertension Pediatric Endocrinology Metabolism

Apparent Manifesting Heterozygosity in P450 Oxidoreductase Deficiency and Its Effect on Coexisting 21-Hydroxylase Deficiency

Division of Endocrinology (R.R.S., L.G.G., N.H., W.L.M.), Department of Pediatrics, University of California, San Francisco, San Francisco, California 94143; and Endocrinology Service and Research Center (R.R.S., G.V.V.), Sainte-Justine Hospital, and Department of Pediatrics, University of Montreal, Montreal, Canada H3T 1C5

Address all correspondence and requests for reprints to: Prof. Walter L. Miller, Pediatric Endocrinology, 672-S, University of California, San Francisco, San Francisco, California 94143-0434. E-mail: wlmlab{at}ucsf.edu.

	Abstract

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

 
Context: P450 oxidoreductase (POR) deficiency is a disorder of steroidogenesis affecting the microsomal P450 enzymes that use POR as an electron donor. The clinical presentation is variable; patients can be asymptomatic or can present with genital anomalies and the Antley-Bixler syndrome, characterized by craniosynostosis and other bony anomalies. Obligately heterozygous parents are normal. Combined POR and 21-hydroxylase deficiencies have not been reported.

Objective: The aim was to explore the manifestations of combined deficiencies of 21-hydroxylase and POR and to search for lesions in apparent manifesting POR heterozygotes.

Patients and Methods: A newborn female had craniosynostosis, severe salt wasting, minimal virilization, grossly elevated 17OH-progesterone, and minimally elevated androgens. DNA encoding 21-hydroxylase, POR, and fibroblast growth factor receptor 2 was sequenced. For POR, the first untranslated exon (exon 1U), 5' flanking DNA, and most introns were sequenced in five apparent manifesting POR heterozygotes.

Results: CYP21B mutations were found on both alleles, proving classical 21-hydroxylase deficiency. Fibroblast growth factor receptor 2 exons 8 and 10 were normal. A POR mutation, A287P, was found only on the maternal allele. Five previously reported patients had POR mutations found on only one allele, but their clinical characteristics were indistinguishable from patients with mutations on both alleles. Sequencing of exon 1U, 274 bp of POR 5' flanking DNA, and 12 of the 15 POR introns did not identify additional mutations affecting gene expression or splicing.

Conclusion: Manifesting heterozygosity is a possible feature of POR deficiency and may ameliorate the findings in coexisting 21-hydroxylase deficiency.

	Introduction

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

 
P450 OXIDOREDUCTASE (POR) deficiency is a newly described autosomal recessive disorder of steroidogenesis (1, 2, 3). POR is the flavoprotein that transfers electrons from nicotinamide adenine dinucleotide phosphate to all 50 microsomal cytochrome P450 enzymes (4). A disorder of steroidogenesis that resembled combined deficiencies of 17-hydroxylase, 17,20 lyase, and 21-hydroxylase was first reported in 1985 (5), and similar patients were reported subsequently (reviewed in Refs. 3 and 6). Despite the early suggestion that this disorder might be caused by mutations in POR (7), the lethality of POR gene ablation in mice (8, 9) implied that human POR mutations would be disastrous. Nevertheless, Flück et al. (1) reported four patients with POR mutations in early 2004, and subsequent reports have documented at least 41 such patients (1, 2, 6, 10, 11, 12). The rapid discovery of so many patients and the observation that POR mutations may cause mild disease without skeletal anomalies (1, 6) suggest that POR deficiency may not be rare, but its diagnosis remains difficult because of the complex pattern of disordered plasma steroids and their urinary metabolites resulting from incomplete interruption of several steps in steroidogenesis.

POR deficiency manifests with and without skeletal anomalies. Most patients described to date have had a congenital malformation disorder termed Antley-Bixler syndrome (ABS), which is characterized by craniosynostosis, radio-ulnar or radio-humeral synostosis, bowed femora, and other skeletal anomalies (13, 14). The craniosynostosis of ABS resembles that of Apert, Crouzon, Pfeiffer, and Jackson-Weiss syndromes. Work in the mid-1990s showed that these craniosynostosis syndromes were caused by dominant, gain-of-function mutations in exons 8 and 10 of the gene for fibroblast growth factor receptor 2 (FGFR2) (reviewed in Refs. 3 and 6). Initial work identified similar (or identical) FGFR2 mutations in some patients with ABS (15), but other patients with ABS had no mutations in FGFR2 (15). ABS patients harboring FGFR2 mutations have normal genitalia, whereas those who also have genital anomalies and/or an abnormal pattern of urinary steroids lack FGFR2 mutations (15). Analysis of the FGFR2 and POR genes in a large group of ABS patients established that the same skeletal malformation syndrome may result from either dominant FGFR2 mutations or recessive POR mutations, and that all ABS patients with genital anomalies or disordered steroidogenesis had POR mutations (6).

POR is required for the activity of three steroidogenic enzymes: P450c17, which catalyzes 17-hydroxylase and 17,20 lyase activities; P450c21, the adrenal 21-hydroxylase; and P450aro, which aromatizes androgens to estrogens. Thus, POR deficiency affects multiple steps in steroidogenesis (Fig. 1). Furthermore, most POR lesions retain partial activity, so that these enzymatic steps may be incompletely blocked. Therefore, the array of disordered steroids seen in blood and urine can be variable, making the diagnosis difficult. POR deficiency can lead to genital ambiguity in both sexes; impairment of testicular P450c17 in severely affected male fetuses leads to incomplete masculinization, whereas impairment of placental aromatase and/or activation of the "backdoor pathway" of androgen biosynthesis (2, 16, 17) leads to partial virilization of female fetuses. The impairment in 17,20 lyase activity is greater than the impairment in 17-hydroxylase activity, consistent with the established enzymology of P450c17 (18, 19, 20); hence, affected individuals typically have moderately elevated concentrations of 17OH-progesterone (17OHP) with an exaggerated response to acute stimulation with ACTH. The values are generally comparable to those seen in nonclassic 21-hydroxylase deficiency (1, 6, 11, 12). Maternal urinary estriol is very low due to impaired feto/placental steroidogenesis (21), and 21-deoxycortisol has been elevated in all patients in whom it has been measured. Basal cortisol is typically normal but poorly responsive to ACTH, indicating compensated adrenal insufficiency, and dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and androstenedione are typically low. Thus, the hormonal data may suggest POR deficiency but may not provide an unambiguous diagnosis; hence DNA sequencing has assumed a more important role in this disease than in other forms of adrenal hyperplasia.

View larger version (18K): [in this window] [in a new window]   FIG. 1. Simplified steroid biosynthetic pathway indicating the steps affected in POR deficiency. POR supports the activities of P450c17, P450c21, and P450aro. Because the 17,20 lyase activity of human P450c17 does not effectively convert 17OHP to androstenedione, 17OHP accumulates when 21-hydroxylase activity is impaired. The combined partial impairment of 17-hydroxylase activity and 21-hydroxylase activity may compromise cortisol synthesis. Because the 17,20 lyase activity of P450c17 is more sensitive to perturbations in electron transfer than is its 17-hydroxylase activity, the synthesis of DHEA, androstenedione, testosterone, and estradiol is more severely affected, so that the typical patient with POR deficiency will have a mildly elevated 17OHP and low C19 steroids.

	Subject and Methods

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

 
DNA sequencing

DNA was collected in accordance with local institutional review board guidelines. CYP21B genetic analysis was done at the Alberta Children’s Hospital molecular diagnostic laboratory. The 15 coding exons of POR, including at least 100 bp of the flanking introns, were sequenced as described (6). We characterized POR exon 1U and the 5' flanking DNA by identifying a region of high homology with the known rat sequence using BLAST from the Ensembl Genome Browser (http://www.ensembl.org/index.html). Primers flanking exon 1U, 274 bp of the 5' flanking DNA, and introns 3, 4, 5, 6, 7, 9, and 11 were designed using the University of California, Santa Cruz genome browser (http://genome.ucsc.edu; accession no. NM_000941) and using Primer 3 (http://frodo.wi.mit.edu/cgi-bin/primer3/primer3_www.cgi) (Table 1). Regions containing known single nucleotide polymorphisms (SNPs) were not used for primers. We performed PCR with a 20:1 mix of Taq (Promega, Madison, WI) and pfu DNA polymerases (Stratagene, Cedar Creek, TX) (22). We amplified introns 3, 4, 5, 6, and 7 (downstream fragment) under touchdown cycling conditions: 95 C for 4 min, then 15 touchdown cycles of 95 C for 30 sec, 62 C for 30 sec (decreasing by 0.5 C with each cycle), and 72 C for 1 min, followed by 25 cycles of 95 C for 30 sec, 55 C for 30 sec, and 72 C for 1 min. The final extension was held at 72 C for 7 min, and then the reaction was stopped at 4 C. We amplified introns 7 (upstream fragment), 9, and 11 as described above, except that the annealing temperature started at 63 C and finished at 56 C after the 15 touchdown cycles and then continued at 56 C for the remaining 25 cycles. Amplification of exon 1U and the 5' flanking DNA was performed under the same conditions except that annealing started at 64 C for 15 touchdown cycles and then continued at 57 C for the remaining 25 cycles. All cycling for PCR was performed on the Bio-Rad MyCycler and i-Cycler (Bio-Rad Laboratories, Hercules, CA); PCR for sequencing was performed on the ABI GeneAmp PCR System 9700 (Applied Biosystems, Foster City, CA). Automated direct sequencing of PCR products employed the primers in Table 1 and ABI BigDye terminator, version 3.1 (Applied Biosystems). Data were displayed with ABI 3730#1 DNA Analyzer and analyzed using Sequencher demo version 4.5 (http://www.genecodes.com).

	Case Report

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

	Results

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

 
DNA sequencing

Sequencing of the CYP21B gene from the patient and her parents identified a deletion of the paternal allele and two mutations on the maternal allele: the severe IVS2–13A/C>G splice site mutation and the mild P30L mutation. Because of the mild, nonprogressive virilization, the craniosynostosis, and the unusual steroid pattern, we also sequenced the POR gene, revealing the common A287P mutation on the maternal allele. No lesions were found on the paternal allele. No mutations were found in exons 8 and 10 of FGFR2, a common genetic cause of craniosynostosis.

Characterization of exon 1U

All previous analyses of the POR gene in patients with apparent POR deficiency have described the POR gene as containing 15 exons and 14 introns (1, 2, 3, 6, 10, 11, 12). However the NCBI Entrez Nucleotide database entry for the human POR cDNA and mRNA included 5' untranslated sequences not found in "exon 1" (www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Nucleotide; accession no. NM_000941.2), and previous studies showed that the rat POR gene contains an untranslated exon 30.5 kb upstream from the first coding exon (23, 24, 25). To determine whether the human gene is organized similarly, we probed the human genome database with the 56-nucleotide sequence of the rat upstream untranslated exon and identified a similar human DNA region about 38.8 kb upstream from what has previously been called exon 1; we term this exon "1U" so as to preserve the numbering from previous studies (1, 2, 3, 6, 10, 11, 12). The 3' end of exon 1U is defined by the mRNA/cDNA sequence (accession no. NM_000941.2) and is immediately followed by a canonical GTGAG splice donor site. The 5' end of the exon has not been defined experimentally, but a putative transcriptional start site has been chosen by analogy with the rat gene, whose transcriptional start site has been identified experimentally (23). Putative promoter regions important for transcription of the rat gene lie immediately upstream and are highly conserved in the human sequence (Fig. 2).

View larger version (27K): [in this window] [in a new window]   FIG. 2. Sequences of human (H) and rat (R). P450 oxidoreductase untranslated exon 1 and 5' flanking DNA, assembled by Ensembl Blast analysis. The vertical lines show identical nucleotide sequences between rat and human. The boxes show human and rat untranslated exon 1. The underscore in the rat sequence represents previously defined regulatory regions, and the dots represent the bases essential for the activity of these regions in the rat promoter.

Our previous reports included five patients in whom we had found only one POR mutation; these included subject 2 (1) and subjects CF1, 259, 337, and 14683 (6). We sought cryptic mutations in our present patient and in those five previous patients by sequencing a 478-bp fragment encompassing exon 1U and 274 bp of 5' flanking, putative promoter DNA, as well as sequencing all of introns 3, 4, 5, 6, 7, 9, and 11. The introns between exons 1U and 1 (38,809 bp), exons 1 and 2 (18,231 bp) and exons 2 and 3 (6,988 bp) were too large for PCR amplification, so that only 100 bp at each end, adjacent to the exons, was sequenced.

Patients 259 and 337 (6) were homozygous for known SNP rs3823884 in the 5' untranslated region of exon 1U in position –47A>C. Our patient had two POR intronic substitutions: IVS6 + 499C>G and IVS11 + 31C>T. Patient CF1 (6) had substitutions IVS6 + 418G>A and IVS11 + 32G>A; no other intronic sequence variants and no promoter sequence variants were found. These intronic nucleotide substitutions are not known SNPs, but we have observed the same intron 11 substitutions in our sequence analysis of 851 normal controls (Huang, N., V. Agrawal, K. M. Giacomini, and W. L. Miller, unpublished data). The location of the intron 6 substitutions was not covered by the sequencing strategy used for normal controls, so we do not know whether these SNPs are present in healthy individuals. Analysis of these nucleotides with NetGene2 (http://www.cbs.dtu.dk/services/NetGene2) indicates that these changes would not disrupt or create a cryptic splice acceptor or donor site.

	Discussion

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

 
To our knowledge, this is the first report of combined deficiencies of CYP21 and POR. A lesion in CYP21 was initially suggested by the high 17OHP and confirmed by DNA sequencing. When combined with a gene deletion, the CYP21 IVS2–13A/C>G splice site mutation is associated with severe salt-wasting congenital adrenal hyperplasia (26, 27). The genotype-phenotype correlation in 21-hydroxylase deficiency is excellent (26, 27), and the degree of elevation in 17OHP tends to correlate with disease severity (28). Our patient’s 17OHP levels at diagnosis were high, but her concentrations of C19 steroids were disproportionately low for the elevation in 17OHP: when her 17OHP was 56,230 ng/dl (1,687 nmol/liter), DHEAS was 29.4 µg/dl (0.8 µmol/liter), androstenedione was 395 ng/dl (13.8 nmol/liter), and testosterone was 49 ng/dl (1.7 nmol/liter). In contrast, from reported serum values in nine newborn females with untreated 21-hydroxylase deficiency (29), we calculated mean values for 17OHP of 12,350 ng/dl (370 nmol/liter), DHEAS of 168 µg/dl (4.6 µmol/liter), androstenedione of 2,458 ng/dl (86 nmol/liter), and testosterone of 195 ng/dl (6.8 nmol/liter). Also, the degree of virilization seen in girls with salt-wasting 21-hydroxylase deficiency is usually more severe, yet our patient was only mildly virilized, and her virilization did not progress over 10 yr of follow-up. This is explained by the associated POR deficiency, which affects the 17,20 lyase activity of P450c17 to a much greater degree than its 17-hydroxylase activity (1, 3, 4, 6), so that 17OHP accumulates, but androgens do not.

POR impairs both the 17-hydroxylase and 17,20 lyase activities of CYP17, partially blocking the formation of androgen via the classical pathway. Virilization in females with POR deficiency appears to arise both from impaired placental aromatase activity and activation of the backdoor pathway to dihydrotestosterone (16, 17, 30). The role of the backdoor pathway is supported by finding increased amounts of androsterone in the urine of a woman carrying a POR-deficient fetus (30) and the observation that CYP17 has greater affinity for 5 reduced C21 steroids than for 17OHP or 17OH-pregnenelone (31). However, the kinetics of the other enzymes in the backdoor pathway are unknown, and the contribution of this pathway to human androgen production is not yet defined. The lack of severe virilization and low C19 steroids both suggest a relative deficiency of androgen synthesis at the level of 17,20 lyase activity secondary to POR deficiency.

A role for POR in our patient was initially suggested by her craniosynostosis in the presence of impaired 17,20 lyase activity and normal FGFR2 gene sequences. Craniosynostosis can be an isolated anomaly or part of a craniosynostosis syndrome, most of which are caused by FGFR mutations. The incidence of craniosynostosis is about 3–5 per 10,000 births, of which 86% is nonsyndromic (32, 33); most syndromic craniosynostosis is caused by gain-of-function mutations in exons 8 or 10 of FGFR2. Craniosynostosis has not been linked to defects of steroidogenesis other than POR deficiency.

POR deficiency is autosomal recessive (1, 2, 3, 6, 10, 11, 12). However, we were only able to find one mutation, A287P, in our patient. Consistent with recessive inheritance, the unaffected mother also carried A287P on one allele. Six of the 41 reported patients (15%) with POR deficiency have only one identified mutation, despite being clinically indistinguishable from patients with two identified mutations (1, 6). This is an unusually high percentage for an autosomal recessive disease. Therefore, we extended the search for POR mutations to include 12 of the 15 introns, exon 1U and the 5' flanking region, but were unable to identify nucleotide variations that appeared to cause abnormal splicing of the transcription product or abnormal regulation of gene expression. A recent brief report mentions that only one mutation was found in two of five patients, but, because clinical descriptions of all of these patients had been reported previously, it is not clear how many additional patients are described (34). Nevertheless, this report strengthens the observation that apparent manifesting heterozygotes of POR are common.

Manifesting heterozygosity occurs frequently in X-linked disorders such as Duchenne muscular dystrophy due to skewed X inactivation (35), but is also described in autosomal recessive disorders; for example, about 17% of thyroid peroxidase deficiency represents manifesting heterozygosity in which only the mutant allele is transcribed into RNA (36). Our six patients may represent a new example of manifesting heterozygosity in an autosomal recessive disease. Because RNA was not available for study from our patients, we cannot be certain whether they represent true manifesting heterozygosity or only apparent heterozygosity, with unidentified mutations or gene silencing via abnormal methylation on the seemingly unaffected allele. Thus, these patients have apparent, but unproven, manifesting heterozygosity.

	Acknowledgments

 
We thank Dr. Maria New (Mt. Sinai Medical Center, New York, NY) for helpful discussions and Dr. Peter Bridges (Alberta Children’s Hospital Molecular Diagnostic Laboratory, Calgary, Alberta) for performing the CYP21 sequencing.

	Footnotes

 
This work was supported by National Institutes of Health Grant GM 073020 (to W.L.M.).

Author Disclosure Summary: All authors have nothing to declare.

First Published Online March 27, 2007

¹ R.R.S. and L.G.G. contributed equally to this work.

Abbreviations: ABS, Antley-Bixler syndrome; DHEA, dehydroepiandrosterone; DHEAS, DHEA sulfate; FGFR2, fibroblast growth factor receptor 2; 17OHP, 17OH-progesterone; POR, P450 oxidoreductase; SNP, single nucleotide polymorphism.

Received October 26, 2006.

Accepted March 19, 2007.

	References

Top Abstract Introduction Subject and Methods Case Report Results Discussion References

 

1. Flück CE, Tajima T, Pandey AV, Arlt W, Okuhara K, Verge CF, Jabs EW, Mendonca BB, Fujieda K, Miller WL 2004 Mutant P450 oxidoreductase causes disordered steroidogenesis with and without Antley-Bixler syndrome. Nat Genet 36:228–230[CrossRef][Medline]
2. Arlt W, Walker EA, Draper N, Ivison HE, Ridle JP, Hammer F, Chalder SM, Borucka-Mankiewicz M, Hauffa BP, Malunowicz EM, Stewart PM, Shackleton CH 2004 Congenital adrenal hyperplasia caused by mutant P450 oxidoreductase and human androgen synthesis: analytical study. Lancet 363:2128–2135[CrossRef][Medline]
3. Miller WL 2004 P450 oxidoreductase deficiency. A new disorder of steroidogenesis with multiple clinical manifestations. Trends Endocrinol Metab 15:311–315[CrossRef][Medline]
4. Miller WL 2005 Regulation of steroidogenesis by electron transfer. Endocrinology 146:2544–2550[Abstract/Free Full Text]
5. Peterson RE, Imperato-McGinley J, Gautier T, Shackleton CHL 1985 Male pseudohermaphroditism due to multiple defects in steroid-biosynthetic microsomal mixed-function oxidases: a new variant of congenital adrenal hyperplasia. N Engl J Med 313:1182–1191[Abstract]
6. Huang N, Pandey AV, Agrawal V, Reardon W, Lapunzina PD, Mowat D, Jabs EW, Van Vliet G, Sack J, Flück CE, Miller WL 2005 Diversity and function of mutations in P450 oxidoreductase in patients with Antley-Bixler syndrome and disordered steroidogenesis. Am J Hum Genet 76:729–749[CrossRef][Medline]
7. Miller WL 1986 Congenital adrenal hyperplasia. N Engl J Med 314:1321–1322[Medline]
8. Shen AL, O’Leary KA, Kasper CB 2002 Association of multiple developmental defects and embryonic lethality with loss of microsomal NADPH-cytochrome P450 oxidoreductase. J Biol Chem 277:6536–6541[Abstract/Free Full Text]
9. Otto DM, Henderson CJ, Carrie D, Davey M, Gundersen TE, Blomhoff R, Adams RH, Tickle C, Wolf CR 2003 Identification of novel roles of the P450 system in early embryogenesis: effects on vasculogenesis and retinoic acid homeostasis. Mol Cell Biol 23:6103–6116[Abstract/Free Full Text]
10. Adachi M, Tachibana K, Asakura Y, Yamamoto T, Hanaki K, Oka A 2004 Compound heterozygous mutation of cytochrome P450 oxidoreductase gene (POR) in two patients with Antley-Bixler syndrome. Am J Med Genet 128A:333–339
11. Fukami M, Horikawa R, Nagai T, Tanaka T, Naiki Y, Sato N, Okuyama T, Nakai H, Soneda S, Tachibana K, Matsuo N, Sato S, Homma K, Nishimura G, Hasegawa T, Ogata T 2005 Cytochrome P450 oxidoreductase gene mutations and Antley-Bixler syndrome with abnormal genitalia and/or impaired steroidogenesis: molecular and clinical studies in 10 patients. J Clin Endocrinol Metab 90:414–426[Abstract/Free Full Text]
12. Fukami M, Hasegawa T, Horikawa R, Ohashi T, Nishimura G, Homma K, Ogata T 2006 Cytochrome P450 oxidoreductase deficiency in three patients initially regarded as having 21-hydroxylase deficiency and/or aromatase deficiency: diagnostic value of urine steroid hormone analysis. Pediatr Res 59:276–280[CrossRef][Medline]
13. DeLozier CD, Antley RM, Williams R, Green N, Heller RM, Bixler D, Engel E 1980 The syndrome of multisynostotic osteodysgenesis with long-bone fractures. Am J Med Genet 7:391–403[CrossRef][Medline]
14. Crisponi G, Porcu C, Piu ME 1997 Antley-Bixler syndrome: case report and review of the literature. Clin Dysmorphol 6:61–68[Medline]
15. Reardon W, Smith A, Honour JW, Hindmarsh P, Das D, Rumsby G, Nelson I, Malcolm S, Ades L, Sillence D, Kumar D, DeLozier-Blanchet C, McKee S, Kelly T, McKeehan WL, Baraister M, Winter RM 2000 Evidence for digenic inheritance in some cases of Antley-Bixler syndrome? J Med Genet 37:26–32[Abstract/Free Full Text]
16. Auchus RJ 2004 The backdoor pathway to dihydrotestosterone. Trends Endocrinol Metab 15:432–438[CrossRef][Medline]
17. Homma K, Hasegawa T, Nagai T, Adachi M, Horikawa R, Fujiwara I, Tajima T, Takeda R, Fukami M, Ogata T 2006 Urine steroid hormone profile analysis in cytochrome P450 oxidoreductase deficiency: implication for the backdoor pathway to dihydrotestosterone. J Clin Endocrinol Metab 91:2643–2649[Abstract/Free Full Text]
18. Geller DH, Auchus RJ, Mendonça BB, Miller WL 1997 The genetic and functional basis of isolated 17,20 lyase deficiency. Nat Genet 17:201–205[CrossRef][Medline]
19. Auchus RJ, Lee TC, Miller WL 1998 Cytochrome b₅ augments the 17,20 lyase activity of human P450c17 without direct electron transfer. J Biol Chem 273:3158–3165[Abstract/Free Full Text]
20. Auchus RJ, Miller WL 1999 Molecular modeling of human P450c17 (17-hydroxylase/17,20-lyase): insights into reaction mechanisms and effects of mutations. Mol Endocrinol 13:1169–1182[Abstract/Free Full Text]
21. Cragun DL, Trumpy SK, Shackleton CHL, Kelley RI, Leslie ND, Mulrooney NP, Hopkin RJ 2004 Undetectable maternal serum uE3 and postnatal abnormal sterol and steroid metabolism in Antley-Bixler syndrome. Am J Med Genet 129A:1–7
22. Wang JT, Lin CJ, Burridge SM, Fu GK, Labuda M, Portale AA, Miller WL 1998 Genetics of vitamin D 1-hydroxylase deficiency in 17 families. Am J Hum Genet 63:1694–1702[CrossRef][Medline]
23. O’Leary KA, Beck TW, Kasper CB 1994 NADPH cytochrome P-450 oxidoreductase gene: identification and characterization of the promoter region. Arch Biochem Biophys 310:452–459[CrossRef][Medline]
24. O’Leary KA, McQuiddy P, Kasper CB 1996 Transcriptional regulation of the TATA-less NADPH cytochrome P-450 oxidoreductase gene. Arch Biochem Biophys 330:271–280[CrossRef][Medline]
25. O’Leary KA, Kasper CB 2000 Molecular basis for cell-specific regulation of the NADPH-cytochrome P450 oxidoreductase gene. Arch Biochem Biophys 379:97–108[CrossRef][Medline]
26. Pinto G, Tardy V, Trivin C, Thalassinos C, Lortat-Jacob S, Nihoul-Fékété C, Morel Y, Brauner R 2003 Follow-up of 68 children with congenital adrenal hyperplasia due to 21-hydroxylase deficiency: relevance of genotype for management. J Clin Endocrinol Metab 88:2624–2633[Abstract/Free Full Text]
27. Stikkelbroeck NM, Hoefsloot LH, de Wijs IJ, Otten BJ, Hermus AR, Sistermans EA 2003 CYP21 gene mutation analysis in 198 patients with 21-hydroxylase deficiency in The Netherlands: six novel mutations and a specific cluster of four mutations. J Clin Endocrinol Metab 88:3852–3859[Abstract/Free Full Text]
28. New MI, Lorenzen F, Lerner AJ, Kohn B, Oberfield S, Pollack M, Dupont B, Stoner E, Levy DJ, Pang S, Levine L 1983 Genotyping steroid 21-hydroxylase deficiency: hormonal reference data. J Clin Endocrinol Metab 57:320–326[Abstract]
29. de Peretti E, Forest MG 1982 Pitfalls in the etiologic diagnosis of congenital adrenal hyperplasia in the early neonatal period. Horm Res 16:10–22[Medline]
30. Shackleton C, Marcos J, Arlt W, Hauffa BP 2004 Prenatal diagnosis of P450 oxidoreductase deficiency (ORD): a disorder causing low pregnancy estriol, maternal and fetal virilization, and the Antley-Bixler syndrome phenotype. Am J Med Genet 129A:105–112
31. Gupta MK, Guryev OL, Auchus RJ 2003 5-Reduced C₂₁ steroids are substrates for human cytochrome P450c17. Arch Biochem Biophys 418:151–160[CrossRef][Medline]
32. Alderman BW, Fernbach SK, Greene C, Mangione EJ, Ferguson SW 1997 Diagnostic practice and the estimated prevalence of craniosyntosis in Colorado. Arch Ped Adolescent Med 151:159–164
33. Singer S, Bower C, Southall P, Goldblatt J 1999 Craniosyntosis in Western Australia, 1980–1994: a population-based study. Am J Med Genet 83:382–387[CrossRef][Medline]
34. Adachi M, Asakura Y, Matsuo M, Yamamoto T, Hanaki K, Arlt W 2006 POR R457H is a global founder mutation causing Antley-Bixler syndrome with autosomal recessive trait. Am J Med Genet A 140:633–635[Medline]
35. Richards CS, Watkins SC, Hoffman EP, Schneider NR, Milsark IW, Katz KS, Cook JD, Kunkel LM, Cortada JM 1990 Skewed X inactivation in a female MZ twin results in Duchenne muscular dystrophy. Am J Hum Genet 46:672–681[Medline]
36. Fugazzola L, Cerutti N, Mannavola D, Vannucchi G, Fallini C, Persani L, Beck-Peccoz P 2003 Monoallelic expression of mutant thyroid peroxidase allele causing total iodide organification defect. J Clin Endocrinol Metab 88:3264–3271[Abstract/Free Full Text]

This article has been cited by other articles:

				L. G. Gomes, N. Huang, V. Agrawal, B. B. Mendonca, T. A. S. S. Bachega, and W. L. Miller The Common P450 Oxidoreductase Variant A503V Is Not a Modifier Gene for 21-Hydroxylase Deficiency J. Clin. Endocrinol. Metab., July 1, 2008; 93(7): 2913 - 2916. [Abstract] [Full Text] [PDF]

				A. V. Pandey, P. Kempna, G. Hofer, P. E. Mullis, and C. E. Fluck Modulation of Human CYP19A1 Activity by Mutant NADPH P450 Oxidoreductase Mol. Endocrinol., October 1, 2007; 21(10): 2579 - 2595. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) All Versions of this Article: 92/6/2318    most recent Author Manuscript (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Scott, R. R. Articles by Miller, W. L. Search for Related Content PubMed PubMed Citation Articles by Scott, R. R. Articles by Miller, W. L. Related Collections Adrenal and Hypertension Pediatric Endocrinology Metabolism