Features of Antley-Bixler syndrome in an infant born to a mother with pregnancy luteoma

Imaging features, clinical characteristics and neonatal outcomes of pregnancy luteoma: A case series and literature review

INTRODUCTION

This study aimed to investigate the imaging features, clinical characteristics and neonatal outcomes of pregnancy luteoma.

MATERIAL AND METHODS

We retrospectively analyzed patients with pregnancy luteoma admitted to the First Affiliated Hospital of Sun Yat-sen University between January 2003 and December 2022. We recorded their imaging features, clinical characteristics and neonatal outcomes. Additionally, we reviewed relevant studies in the field.

RESULTS

In total, 127 cases were identified, including eight from our hospital and 119 from the literature. Most patients (93/127, 73.23%) were of reproductive age, 20-40 years old, and 66% were parous. Maternal hirsutism or virilization (such as deepening voice, acne, facial hair growth and clitoromegaly) was observed in 29.92% (38/127), whereas 59.06% of patients (75/127) were asymptomatic. Abdominal pain was reported in 13 patients due to compression, torsion or combined ectopic pregnancy. The pregnancy luteomas, primarily discovered during the third trimester (79/106, 74.53%), varied in size ranging from 10 mm to 20 cm in diameter. Seventy-five cases were incidentally detected during cesarean section or postpartum tubal ligation, and 39 were identified through imaging or physical examination during pregnancy. Approximately 26.61% of patients had bilateral lesions. The majority of pregnancy luteomas were solid and well-defined (94/107, 87.85%), with 43.06% (31/72) displaying multiple solid and well-circumscribed nodules. Elevated serum androgen levels (reaching values between 1.24 and 1529 times greater than normal values for term gestation) were observed in patients with hirsutism or virilization, with a larger lesion diameter (P < 0.001) and a higher prevalence of bilateral lesions (P < 0.001). Among the female infants born to masculinized mothers, 68.18% (15/22) were virilized. Information of imaging features was complete in 22 cases. Ultrasonography revealed well-demarcated hypoechoic solid masses with rich blood supply in 12 of 19 cases (63.16%). Nine patients underwent magnetic resonance imaging (MRI) or computed tomography (CT), and six exhibited solid masses, including three with multi-nodular solid masses.

CONCLUSIONS

Pregnancy luteomas mainly manifest as well-defined, hypoechoic and hypervascular solid masses. MRI and CT are superior to ultrasonography in displaying the imaging features of multiple nodules. Maternal masculinization and solid masses with multiple nodules on imaging may help diagnose this rare disease.

An Investigation of the Relationship Between the Second-to-Fourth Digit Ratio and Sagittal Synostosis

BACKGROUND

The most common presentation of nonsyndromic craniosynostosis is that of the sagittal suture. Amongst this subgroup there is a significant male preponderance. Although the etiology is largely unknown, androgen exposure in utero has been suggested as a contributing factor. The second-to-fourth digit ratio (2D:4D) is a sexually dimorphic trait, reflective of the levels of androgen and estrogen exposure in utero, with a lower 2D:4D ratio associated with higher androgen exposure.This study aimed to examine the difference in 2D:4D ratio between participants with sagittal synostosis (SS) and gender-matched controls, hypothesizing that alterations in androgen exposure would be reflected in participants' 2D:4D ratio.

METHOD

Participants with nonsyndromic SS and gender-matched controls were prospectively recruited from outpatients clinics. Photographs were taken of the right hand, and 3 independent researchers measured the length of the fingers and 2D:4D ratio, with the mean 2D:4D ratio then calculated.

RESULTS

Fifty-six participants were recruited to both groups, with 35 males and 21 females in each. The mean age of the study and control groups were 5.6 and 6.3 years, respectively. There was no difference in the 2D:4D ratio between groups overall (P = 0.126). However, males with SS had a significantly higher 2D:4D ratio in comparison to male controls (0.969 ± 0.379 versus 0.950 ± 0.354, P = 0.038).

CONCLUSIONS

Our results suggest that 1 single hormonal pathway is not responsible for suture fusion. Subsequently we consider that an imbalance between testosterone and estrogen signaling may contribute to the development of sagittal craniosynostosis.

Hirsutism Caused by Pregnancy Luteoma in a Low-Resource Setting: A Case Report and Literature Review

BACKGROUND

Pregnancy luteomas are rare, benign, ovarian neoplasms resulting from increased androgenic activity during pregnancy. Often, they occur asymptomatically and are only diagnosed incidentally during imaging or surgery: cesarean section or postpartum tubal ligation. Most common symptoms associated with pregnancy luteoma include acne, deepening of voice, hirsutism, and clitoromegaly. Most pregnancy luteomas regress spontaneously postpartum. Thus, the management of pregnancy luteomas depends on the clinical situation.

CASE

We report a case of 28-year-old gravida 2, para 1 who presented at 39 + 1 weeks of gestation with prolonged labor and delivered by emergency cesarean. Intraoperatively, a huge left ovarian mass was identified and resected, and tissue was sent for histopathology and a diagnosis of pregnancy luteoma was made after the pathological report.

CONCLUSION

The present report emphasizes that pregnancy luteoma is a benign neoplasm and imprudent surgical intervention should be reserved. Proper imaging techniques, preferably MRI or ultrasonography that visualize the size of the ovary and reproductive hormonal profiles, would suffice for the diagnosis and management of pregnancy luteoma.

46,XX DSD due to Androgen Excess in Monogenic Disorders of Steroidogenesis: Genetic, Biochemical, and Clinical Features

The term 'differences of sex development' (DSD) refers to a group of congenital conditions that are associated with atypical development of chromosomal, gonadal, or anatomical sex. Disorders of steroidogenesis comprise autosomal recessive conditions that affect adrenal and gonadal enzymes and are responsible for some conditions of 46,XX DSD where hyperandrogenism interferes with chromosomal and gonadal sex development. Congenital adrenal hyperplasias (CAHs) are disorders of steroidogenesis that mainly involve the adrenals (21-hydroxylase and 11-hydroxylase deficiencies) and sometimes the gonads (3-beta-hydroxysteroidodehydrogenase and P450-oxidoreductase); in contrast, aromatase deficiency mainly involves the steroidogenetic activity of the gonads. This review describes the main genetic, biochemical, and clinical features that apply to the abovementioned conditions. The activities of the steroidogenetic enzymes are modulated by post-translational modifications and cofactors, particularly electron-donating redox partners. The incidences of the rare forms of CAH vary with ethnicity and geography. The elucidation of the precise roles of these enzymes and cofactors has been significantly facilitated by the identification of the genetic bases of rare disorders of steroidogenesis. Understanding steroidogenesis is important to our comprehension of differences in sexual development and other processes that are related to human reproduction and fertility, particularly those that involve androgen excess as consequence of their impairment.

Genotype-phenotype analysis in congenital adrenal hyperplasia due to P450 oxidoreductase deficiency

CONTEXT

P450 oxidoreductase deficiency (PORD) is a unique congenital adrenal hyperplasia variant that manifests with glucocorticoid deficiency, disordered sex development (DSD), and skeletal malformations. No comprehensive data on genotype-phenotype correlations in Caucasian patients are available.

OBJECTIVE

The objective of the study was to establish genotype-phenotype correlations in a large PORD cohort.

DESIGN

The design of the study was the clinical, biochemical, and genetic assessment including multiplex ligation-dependent probe amplification (MLPA) in 30 PORD patients from 11 countries.

RESULTS

We identified 23 P450 oxidoreductase (POR) mutations (14 novel) including an exonic deletion and a partial duplication detected by MLPA. Only 22% of unrelated patients carried homozygous POR mutations. p.A287P was the most common mutation (43% of unrelated alleles); no other hot spot was identified. Urinary steroid profiling showed characteristic PORD metabolomes with variable impairment of 17α-hydroxylase and 21-hydroxylase. Short cosyntropin testing revealed adrenal insufficiency in 89%. DSD was present in 15 of 18 46,XX and seven of 12 46,XY individuals. Homozygosity for p.A287P was invariably associated with 46,XX DSD but normal genitalia in 46,XY individuals. The majority of patients with mild to moderate skeletal malformations, assessed by a novel scoring system, were compound heterozygous for missense mutations, whereas nearly all patients with severe malformations carried a major loss-of-function defect on one of the affected alleles.

CONCLUSIONS

We report clinical, biochemical, and genetic findings in a large PORD cohort and show that MLPA is a useful addition to POR mutation analysis. Homozygosity for the most frequent mutation in Caucasians, p.A287P, allows for prediction of genital phenotype and moderate malformations. Adrenal insufficiency is frequent, easily overlooked, but readily detected by cosyntropin testing.

The effects of testosterone on craniosynostotic calvarial cells: a test of the gene/environmental model of craniofacial anomalies

INTRODUCTION

The gene-environmental interaction model for craniofacial development proposes that if a genetic predisposition for an anomaly is coupled with an environmental factor that can exacerbate this predisposition, more severe phenotypes will result. Here, we utilize cells derived from our non-syndromic rabbit model of craniosynostosis to test the hypothesis that an insult, testosterone (TP) administration (exogenous source) will alter the osteogenic activity of these cells.

DESIGN

Calvarial cells from wild-type (WT) (N=13) or craniosynostotic (CS) rabbits (N=11) were stimulated with TP, an androgen receptor blocker, flutamide, and combined treatments. Proliferation and differentiation assays were conducted after 7 days. anova and t-tests were used to determine differences in stimulation and cell type.

RESULTS

The CS cells had significantly greater proliferation after TP administration compared to WT. There were no appreciable changes in differentiation after TP stimulation. Flutamide administration or combined TP and flutamide administration decreased both proliferation and differentiation for both cell types similarly.

CONCLUSIONS

Testosterone exposure caused an increase in cell proliferation for CS osteoblast cells. However, a therapy targeted to mitigate this response (flutamide therapy) similarly affected CS and WT cells, suggesting that the administration of flutamide or TP in the presence of flutamide decreases osteogenesis of these cells. Thus, although our data support a mechanism of gene-environmental interaction, these results would not support a therapeutic intervention based on this interaction.

Foot anomalies in Antley-Bixler syndrome: three case reports

Multiple joint contractures, including radiohumeral synostosis, are the hallmark of Antley-Bixler syndrome (ABS). The detailed description of the skeletal aberration, however, focused in feet is scarce. We carried out the scrutiny for foot lesion in three ABS patients with POR (nicotinamide adenine dinucleotide phosphate-oxidase-cytochrome P450 oxidoreductase) gene mutations, one of whom had undergone surgical intervention for difficulty in walking. Radiographs in all three patients showed middle cuneiform-second metatarsal synostosis and the fourth brachymetapody, irrespective of the severity of their systemic manifestations. In addition, talocalcaneal synostosis, lateral cuneiform-cuboid synostosis, defects of middle phalanx, and distal phalanx-middle phalanx synostosis were found in at least two patients. In conclusion, we found distinctive constellations of foot abnormalities in the patients of ABS with POR gene mutation, which may be useful in planning the treatment strategy, as well as in the diagnostic process.

Proximal femoral focal deficiency as a manifestation of Antley-Bixler syndrome: a case report

We report a case of the Antley-Bixler syndrome in an 11-year-old girl. She presented with bilateral proximal femoral focal deficiency, right clubfoot, left radiohumeral synostosis, bilateral ear hypoplasia, cleft palate, tongue tie, missing teeth, congenital heart disease, a pelvic kidney with hydronephrosis, and mental retardation. Proximal femoral focal deficiency has never been reported before as a manifestation of Antley-Bixler syndrome. Her mother was exposed to radiation during an intravenous urogram done in the first trimester of pregnancy. Exposure to radiation has not been implicated as a cause of Antley-Bixler syndrome.

Linking Antley–Bixler syndrome and congenital adrenal hyperplasia: A novel case of P450 oxidoreductase deficiency

The Antley-Bixler syndrome (ABS) is a multiple congenital malformation syndrome with craniosynostosis, radiohumeral synostosis, femoral bowing, choanal atresia or stenosis, joint contractures, urogenital abnormalities and, often, early death. Autosomal recessive and dominant inheritance have been postulated, as has fluconazole teratogenesis. Mutations in POR (P450 (cytochrome) oxidoreductase, an essential electron donor to enzymes participating in cholesterol biosynthesis), have been identified in some patients with the ABS phenotype. Recent evidence suggests that these mutations cause attenuated steroid hydroxylation, which in turn, causes congenital adrenal hyperplasia (CAH) with ambiguous genitalia in both sexes and glucocorticoid deficiency. Here, we report on a new patient with findings of both ABS and CAH that further illustrates how low maternal estriol at prenatal screening can serve as a marker steroid facilitating early diagnosis.

P450 oxidoreductase deficiency: a new form of congenital adrenal hyperplasia

PURPOSE OF REVIEW

P450 oxidoreductase deficiency--a newly described form of congenital adrenal hyperplasia--typically presents a steroid profile suggesting combined deficiencies of steroid 21-hydroxylase and 17alpha-hydroxylase/17,20-lyase activities. These and other enzymes require electron donation from P450 oxidoreductase. The clinical spectrum of P450 oxidoreductase deficiency ranges from severely affected children with ambiguous genitalia, adrenal insufficiency and the Antley-Bixler skeletal malformation syndrome to mildly affected individuals with polycystic ovary syndrome. We review current knowledge of P450 oxidoreductase deficiency and its broader implications.

RECENT FINDINGS

Since the first report in 2004, at least 21 P450 oxidoreductase mutations have been reported in over 40 patients. The often subtle manifestations of P450 oxidoreductase deficiency suggest it may be relatively common. P450 oxidoreductase deficiency, with or without Antley-Bixler syndrome, is autosomal recessive, whereas Antley-Bixler syndrome without disordered steroidogenesis is caused by autosomal dominant fibroblast growth factor receptor 2 mutations. In-vitro assays of P450 oxidoreductase missense mutations based on P450 oxidoreductase-supported P450c17 activities provide excellent genotype/phenotype correlations. The causal connection between P450 oxidoreductase deficiency and disordered bone formation remains unclear.

SUMMARY

P450 oxidoreductase mutations cause combined partial deficiency of 17alpha-hydroxylase and 21-hydroxylase. Individuals with an Antley-Bixler syndrome-like phenotype presenting with sexual ambiguity or other abnormalities in steroidogenesis should be analyzed for P450 oxidoreductase deficiency.

Molecular basis of adrenal insufficiency

Defective production of adrenal steroids due to either primary adrenal failure or hypothalamic-pituitary impairment of the corticotrophic axis causes adrenal insufficiency. Depending on the etiologies of adrenal insufficiency, clinical manifestations may be severe or mild, have gradual or sudden onset, begin in infancy or childhood/adolescence. Adrenal crisis represents an endocrine emergency, and thus the rapid recognition and prompt therapy for adrenal crisis are critical for survival even before the diagnosis is made. The recognition of various disorders that cause adrenal insufficiency, either at a clinical or molecular level, often has implications for the management of the patient. Recent molecular-genetic analysis for the disorder that causes adrenal insufficiency gives valuable insights into the adrenal organogenesis, the regulation of steroid hormone biosynthesis, and the developmental and reproductive endocrinology. In this review we present the latest information on the molecular basis of adrenal insufficiency, with special emphasis on congenital lipoid adrenal hyperplasia, P450-oxidoreductase deficiency, and adrenal hypoplasia congenita.

Diversity and function of mutations in p450 oxidoreductase in patients with Antley-Bixler syndrome and disordered steroidogenesis

P450 oxidoreductase (POR) is the obligatory flavoprotein intermediate that transfers electrons from reduced nicotinamide adenine dinucleotide phosphate (NADPH) to all microsomal cytochrome P450 enzymes. Although mouse Por gene ablation causes embryonic lethality, POR missense mutations cause disordered steroidogenesis, ambiguous genitalia, and Antley-Bixler syndrome (ABS), which has also been attributed to fibroblast growth factor receptor 2 (FGFR2) mutations. We sequenced the POR gene and FGFR2 exons 8 and 10 in 32 individuals with ABS and/or hormonal findings that suggested POR deficiency. POR and FGFR2 mutations segregated completely. Fifteen patients carried POR mutations on both alleles, 4 carried mutations on only one allele, 10 carried FGFR2 or FGFR3 mutations, and 3 patients carried no mutations. The 34 affected POR alleles included 10 with A287P (all from whites) and 7 with R457H (four Japanese, one African, two whites); 17 of the 34 alleles carried 16 "private" mutations, including 9 missense and 7 frameshift mutations. These 11 missense mutations, plus 10 others found in databases or reported elsewhere, were recreated by site-directed mutagenesis and were assessed by four assays: reduction of cytochrome c, oxidation of NADPH, support of 17alpha-hydroxylase activity, and support of 17,20 lyase using human P450c17. Assays that were based on cytochrome c, which is not a physiologic substrate for POR, correlated poorly with clinical phenotype, but assays that were based on POR's support of catalysis by P450c17--the enzyme most closely associated with the hormonal phenotype--provided an excellent genotype/phenotype correlation. Our large survey of patients with ABS shows that individuals with an ABS-like phenotype and normal steroidogenesis have FGFR mutations, whereas those with ambiguous genitalia and disordered steroidogenesis should be recognized as having a distinct new disease: POR deficiency.

Biochemical diagnosis of Antley-Bixler syndrome by steroid analysis

Antley-Bixler syndrome (ABS, MIM 207410) is a skeletal abnormality syndrome primarily affecting head and limbs. Little is known of the origin of the condition but inactivating mutations in the fibroblast growth factor receptor (FGFR2) has been found in some patients. Genital ambiguity is seen occasionally in this condition, suggesting possible disordered steroidogenesis in early pregnancy. We report the steroid excretion of eight patients diagnosed with the syndrome and one with a related condition, a mild phenotype of the disorder since skeletal and genital abnormalities were not evident. The steroid excretion pattern was consistent and very distinctive in all nine patients. Metabolites of the two primary precursors of steroid hormones, pregnenolone and progesterone, were elevated as were the classical diagnostic metabolites for 17- and 21-hydroxylase deficiencies. Cortisol production was typically within the normal range but generally had blunted response to ACTH. Androgen metabolite excretion tends to be low in patients over 2 months of age, but may be elevated in the newborn period. The metabolome suggested attenuated steroid hydroxylation (including 17,20-lyase activity) although underlying cause is yet to be established. Mutations in CYP17 and CYP21 have not been found and currently the prime suspect is an abnormality in an essential redox partner (P450 oxidoreductase). This paper proposes use of the distinctive steroid metabolome as the primary biochemical parameter for diagnosis of ABS, at least the form not associated with FGFR2 mutations.

Undetectable maternal serum uE3 and postnatal abnormal sterol and steroid metabolism in Antley-Bixler syndrome

Antley-Bixler syndrome (ABS) is a rare condition characterized by radiohumeral synostosis, craniosynostosis, midface hypoplasia, bowing of the femora, multiple joint contractures, and urogenital defects. Several reports have implicated errors of steroid or sterol metabolism in the pathogenesis of ABS. Evidence for this has included association with maternal luteomas, fetal 21-hydroxylase deficiency, early pregnancy exposure to high-dose fluconazole, lanosterol 14-alpha-demethylase deficiency, and a unique urinary steroid profile consistent with apparent pregnene hydroxylation deficiency (APHD). We report two sibs with classic ABS. During both pregnancies, mid-trimester maternal serum screening demonstrated undetectable levels of uncongugated estriol (uE3). The brother had ambiguous genitalia and increased serum levels of progesterone and 17-alpha-hydroxyprogesterone. Postnatal tests performed on the sister demonstrated both the unique urinary steroid profile that defines APHD and evidence of impaired lanosterol 14-alpha-demethylase activity. Our results suggest that in at least some patients with ABS, the skeletal findings and altered steroidogenesis are not associated with genes specific to individual sterol or steroid pathways but rather are related to an element, such as NADPH cytochrome P450 reductase (CPR) or cytochrome b5 (CYb5), that is common to all of these pathways.

Abnormal steroidogenesis in three patients with Antley-Bixler syndrome: apparent decreased activity of 17alpha-hydroxylase, 17,20-lyase and 21-hydroxylase

BACKGROUND

Antley-Bixler syndrome (ABS) is characterized mainly by abnormal skeletal morphogenesis such as craniosynostosis and radiohumeral synostosis, and by ambiguous genitalia in some cases. The mechanisms resulting in these deformities have not been determined.

METHODS

The adrenal and gonadal function of three Japanese ABS patients were evaluated. Patient 1 (17-year-old-male) had bilateral cryptoorchidism, delayed puberty and symptoms of glucocorticoid deficiency. Patient 2 (14-year-old male) and patient 3 (4-year-old female) presented with emaciation. Additionally, patient 3 had partial labial fusion and common urogenital sinus. In each patient, blood sampling for steroid analysis before and after rapid adrenocorticotropic hormone (ACTH) stimulation was carried out. Additionally, urinary steroids were quantified. Molecular analysis of CYP17 and CYP21A2 were also performed.

RESULTS

All patients showed elevated basal 17alpha-deoxysteroid levels. Although the 17alpha-deoxysteroid levels further increased after rapid ACTH stimulation, 17alpha-hydroxysteroids including cortisol did not respond, suggesting impaired 17alpha-hydroxylation. Patient 1 and patient 2 showed low adrenal androgen blood levels both before and after rapid ACTH stimulation. Patient 3 showed lower than normal excretions of urinary androgens. Additionally, a prolonged ACTH stimulation in patient 3 failed to elicit significant increase of adrenal androgens. These findings suggested impaired 17,20-lyase activity. In contrast to attenuated 17alpha-hydroxycorticosteroids, notably cortisol, elevated 17alpha-hydroxyprogesterone (17OHP) levels were observed, not only in pubertal patients (1 and 2) but also in prepubertal patient 3, indicating impaired 21-hydroxylation. This assumption was supported by increased urinary 21-deoxycortisol metabolite excretion in patients 2 and 3. With the exception of a heterozygous mutation of CYP17 in one of the patients, other mutations of this gene or CYP21A2 were identified in any of the patients.

CONCLUSION

Combined decreased 17alpha-hydroxylation, 17,20-lyase activity and 21-hydroxylation was detected in three ABS patients. Considering that the enzymes responsible are all cytochrome P450 enzymes and that another cytochrome P450 enzyme, lanosterol 14alpha-demethylase, has recently been shown to be impaired in an ABS patient, we speculate that dysfunction of a system which commonly regulates cytochrome P 450 activity may be responsible for the ABS phenotype.

P450 oxidoreductase deficiency: a new disorder of steroidogenesis with multiple clinical manifestations

Combined partial deficiency of 17alpha-hydroxylase and 21-hydroxylase is well-described, but patients' genes for these enzymes lack mutations. Recent work has identified mutations in the gene for P450 oxidoreductase (POR) in such patients. POR-deficient individuals have a broad range of disorders, from infants with congenital malformations to women with the polycysic ovary syndrome. POR transfers electrons to all microsomal P450 enzymes: its deficiency affects steroidogenesis, drug metabolism and other processes.

Congenital adrenal hyperplasia caused by mutant P450 oxidoreductase and human androgen synthesis: analytical study

BACKGROUND

Congenital adrenal hyperplasia with apparent combined P450C17 and P450C21 deficiency is associated with accumulation of steroid metabolites, indicating impaired activity of 17alpha-hydroxylase and 21-hydroxylase. However, no mutations have been reported in the CYP17 and CYP21 genes, which encode these P450 enzymes. Affected girls are born with ambiguous genitalia, but their circulating androgens are low, and virilisation does not progress. We aimed to investigate the underlying molecular basis of congenital adrenal hyperplasia with apparent combined P450C17 and P450C21 deficiency in affected children.

METHODS

We did sequence analysis of the human gene encoding P450 oxidoreductase, an enzyme that is important in electron transfer from NADPH to P450C17 and P450C21. We studied two unrelated families with a total of three affected children and 100 healthy controls. Wild-type and mutant P450 oxidoreductase proteins were bacterially expressed, purified, and assayed for cytochrome c reductase activity.

FINDINGS

We identified four mutations encoding single aminoacid changes in P450 oxidoreductase. All patients were compound heterozygotes, whereas their parents and an unaffected sibling harboured a mutation in only one allele. By contrast, no mutations were noted in the controls. Bacterial expression of recombinant mutant proteins revealed deficient or reduced enzyme activity.

INTERPRETATION

Molecular pathogenesis of this form of congenital adrenal hyperplasia is caused by mutations in the gene encoding P450 oxidoreductase. Deficiency of this enzyme could suggest an alternative pathway in human androgen synthesis, present only in fetal life, which explains the combination of antenatal androgen excess and postnatal androgen deficiency.

Mutant P450 oxidoreductase causes disordered steroidogenesis with and without Antley-Bixler syndrome

Deficient activities of multiple steroidogenic enzymes have been reported without and with Antley-Bixler syndrome (ABS), but mutations of corresponding cytochrome P450 enzymes have not been found. We identified mutations in POR, encoding P450 oxidoreductase, the obligate electron donor for these enzymes, in a woman with amenorrhea and three children with ABS, even though knock-out of POR is embryonically lethal in mice. Mutations of POR also affect drug-metabolizing P450 enzymes, explaining the association of ABS with maternal fluconazole ingestion.

Prenatal diagnosis of P450 oxidoreductase deficiency (ORD): A disorder causing low pregnancy estriol, maternal and fetal virilization, and the Antley-Bixler syndrome phenotype

We report studies on the second pregnancy of a woman who had previously given birth to a virilized female infant. The cause of the virilization had not been established, but common forms of congenital adrenal hyperplasia (CAH) were excluded. Longitudinal monitoring of the second pregnancy revealed that estriol excretion failed to increase normally, reaching a maximum 0.7 mg/24 hr at the end of pregnancy (normal mean 30 mg/24 hr). The mother showed signs of virilization by the 23rd week of gestation and aromatase deficiency was suspected. However, predicted urinary metabolites for diagnosis of aromatase deficiency (for example, 16alpha-hydroxyandrosterone) were not increased significantly during the pregnancy. Interestingly, excretion of the androgen metabolite androsterone increased rapidly at the beginning of pregnancy and peaked around the 20th week, suggesting increased production of testosterone and 5alphaDHT, probably the cause of maternal virilization. Urine steroid analysis by GC/MS showed gradually increasing excretion (9 mg/24 hr) of the normally minor metabolite 5alpha-pregnane-3beta,20alpha-diol (epiallopregnanediol), an epimer of the dominant progesterone metabolite pregnanediol (5beta-pregnane-3alpha,20alpha-diol). We believe epiallopregnanediol is largely the maternal urinary excretion product of fetal 5-pregnene-3beta,20alpha-diol, the principal metabolite of pregnenolone, implying a build-up of the latter steroid in the fetal adrenal. These findings suggested that the 'block' in the estriol biosynthetic pathway occurs at an early stage with 17-hydroxylation of pregnenolone being affected. The male baby born of this pregnancy had normal genitalia but showed a urinary steroid profile indicating partial deficiencies of P450c17 and P450c21. However, no mutations in the corresponding CYP17 and CYP21 genes were identified. Urinary steroid analysis carried out on his virilized older sibling showed the same pattern of metabolites. Recently, we determined that this disorder is caused by mutations in P450 oxidoreductase (OR), the essential redox partner for CYP17 and CYP21 hydroxylases. The novel metabolic profile has now been seen in many patients, most diagnosed with the skeletal dysplasia Antley-Bixler syndrome. We propose that excessive excretion of epiallopregnanediol together with low estriol may be prenatally diagnostic for OR deficiency (ORD).

Compound heterozygous mutations of cytochrome P450 oxidoreductase gene (POR) in two patients with Antley-Bixler syndrome

Antley-Bixler syndrome (ABS) is characterized by skeletal defects including craniosynostosis and radiohumeral synostosis. Although mutations in the FGFR2 gene have been found in some patients called ABS, genetic heterogeneity of this syndrome has been proposed. We have previously reported three ABS patients with unique abnormalities in steroidogenesis (apparent decreased activity of 17alpha-hydroxylase, 17,20-lyase, and 21-hydroxylase). Decreased activity of lanosterol 14alpha-demethylase has also been described in an ABS patient. Since all these enzymes require cytochrome P450 oxidoreductase (encoded by POR) as an electron donor, we studied POR in two unrelated ABS patients with abnormal steroidogenesis. Direct sequencing of POR revealed that both patients had compound heterozygous mutations (1329insC and R454H in a male patient, 1698insC and R454H in a female patient). The two insertional mutations were assumed to generate truncated and unstable mRNAs. The R454H mutation was assumed to be deleterious because the R454 resides in the FAD-binding domain and is highly conserved among diverse species. Our results demonstrate that mutations in POR cause the ABS phenotype with autosomal recessive inheritance and with characteristic abnormalities in steroidogenesis.

Abnormal sterol metabolism in a patient with Antley-Bixler syndrome and ambiguous genitalia

Antley-Bixler syndrome (ABS) is a rare multiple anomaly syndrome comprising radiohumeral synostosis, bowed femora, fractures of the long bones, premature fusion of the calvarial sutures, severe midface hypoplasia, proptosis, choanal atresia, and, in some, ambiguous genitalia. Of fewer than 40 patients described to date, most have been sporadic, although reports of parental consanguinity and affected sibs of both sexes suggests autosomal recessive inheritance in some families. Known genetic causes among sporadic cases of ABS or ABS-like syndromes are missense mutations in the IgII and IgIII regions of FGFR2, although the assignment of the diagnosis of ABS to such children has been disputed. A third cause of an ABS-like phenotype is early in utero exposure to fluconazole, an inhibitor of lanosterol 14-alpha-demethylase. The fourth proposed cause of ABS is digenic inheritance combining heterozygosity or homozygosity for steroid 21-hydroxylase deficiency with effects from a second gene at an unknown locus. Because fluconazole is a strong inhibitor of lanosterol 14-alpha-demethylase (CYP51), we evaluated sterol metabolism in lymphoblast cell lines from an ABS patient without a known FGFR2 mutation and from a patient with an FGFR2 mutation and ABS-like manifestations. When grown in the absence of cholesterol to stimulate cholesterol biosynthesis, the cells from the ABS patient with ambiguous genitalia but without an FGFR2 mutation accumulated markedly increased levels of lanosterol and dihydrolanosterol. Although the abnormal sterol profile suggested a deficiency of lanosterol 14-alpha-demethylase, mutational analysis of its gene, CYP51, disclosed no obvious pathogenic mutation in any of its 10 exons or exon-intron boundaries. Sterol metabolism in lymphoblasts from the phenotypically unaffected mother was normal. Our results suggest that ABS can occur in a patient with an intrinsic defect of cholesterol biosynthesis at the level of lanosterol 14-alpha-demethylase, although the genetic nature of the deficiency remains to be determined.