Delayed diagnosis of disorder of sex development (DSD) due to P450 oxidoreductase (POR) deficiency.

CASE PRESENTATION: A 36-year old man, operated on for cryptorchidism at the age of 8 years, was referred to the Outpatient Clinic of Reproductive Endocrinology for investigation of infertility. Clinical examination revealed ambiguous genitalia: penis 4-5 cm, testicular volume 2-3 ml, hypospadias, hypertrophic foreskin and scrotum bifida. Mild hypertension was confirmed. No skeletal malformations were detected. DESIGN: Hormonal and electrolytic determinations as well as semen analysis were conducted. PCR of the coding regions of 17-hydroxylase/17,20 lyase (P450c17) and of P450 oxidoreductase (POR) genes was also performed. RESULTS: Normal levels of electrolytes, low levels of androgens, high levels of gonadotropins and 17-hydroxyprogesterone as well as azoospermia were detected. Karyotype was shown to be 46,XY. Both hCG and ACTH stimulation significantly increased 17-hydroxyprogesterone with no increase in androgens. The diagnosis was congenital adrenal hyperplasia with apparent combined P450c17 and P450c21 deficiency due to mutations in the POR gene. Sequencing of the POR gene revealed: one deletion in exon 12 (Del 1696_1698delGTC >del531Valine) and one missense mutation in exon 7 (A259G) as well as two polymorphisms: rs1057868 (C/T A503V) and rs1057870 (G/A S572S) in exons 12 and 13, respectively. No nucleotide changes were detected in the 8 exons of P450c17. CONCLUSIONS: Molecular findings were consistent with the diagnosis of P450 oxidoreductase deficiency. Despite this severe deficiency, skeletal malformations simulating Antley-Bixler syndrome, which usually characterize the most severe forms, were not confirmed. This discrepancy could be attributed to the differential impact of a POR variant on each one of the P450 enzymes.

P450 oxidoreductase deficiency with maternal virilization during pregnancy.

PURPOSE: The authors report on a rare case of maternal virilization during pregnancy caused by autosomal recessive P450 oxidore- ductase (POR) deficiency. MATERIALS AND METHODS: A 24-year-old primigravida developed a deepening voice and hirsutism in the second trimester. Prenatal ultrasonography failed to detect any fetal abnormality and fetal growth was normal. POR deficiency was suspected, but the mother declined fetal genetic testing. A female neonate was delivered by cesarean section at 41 weeks' gestation. RESULTS: The neonate had skeletal abnormalities. Mutational analysis of the POR gene demonstrated homozygosity for c.1370 G>A and p.R457H in the patient and heterozygosity in her parents. POR deficiency was confirmed in the neonate. CONCLUSION: POR deficiency should be suspected in cases of maternal virilization. Maternal urinary estriol, fetal magnetic resonance imaging, and parental genetic testing should be performed. Parental consent for fetal genetic testing should be sought to ensure prompt diagnosis and early treatment.

Conditional deletion of cytochrome p450 reductase in osteoprogenitor cells affects long bone and skull development in mice recapitulating antley-bixler syndrome: role of a redox enzyme in development.

NADPH-cytochrome P450 oxidoreductase (POR) is the primary electron donor for cytochromes P450, dehydrocholesterol reductase, heme oxygenase, and squalene monooxygenase. Human patients with specific mutations in POR exhibit severe developmental malformations including disordered steroidogenesis, sexual ambiguities and various bone defects, similar to those seen in patients with Antley-Bixler syndrome (ABS). To probe the role of POR during bone development, we generated a conditional knockout mouse (CKO) by cross breeding Por (lox/lox) and Dermo1 Cre mice. CKO mice were smaller than their littermate controls and exhibited significant craniofacial and long bone abnormalities. Differential staining of the CKO mice skull bases shows premature fusion of the sphenooccipital and basioccipital-exoccipital synchondroses. Class III malocclusion was noted in adult knockout mice with an unusual overgrowth of the lower incisors. Shorter long bones were observed along with a reduction in the bone volume fraction, measured by microCT, in the Por-deleted mice compared to age- and sex-matched littermate controls. Concerted up- or down-regulation of proteins in the FGF signaling pathway observed by immunohistochemistry in the tibia samples of CKO mice compared to wild type controls shows a decrease in the FGF signaling pathway. To our knowledge, this is the first report of a mouse model that recapitulates both skull and long bone defects upon Por deletion, offering an approach to study the sequelae of POR mutations. This unique model demonstrates that P450 metabolism in bone itself is potentially important for proper bone development, and that an apparent link exists between the POR and FGF signaling pathways, begging the question of how an oxidation-reduction flavoprotein affects developmental and cellular signaling processes.

46,XX DSD: the masculinised female.

The 46,XX disorders of sex development (DSDs) cause virilisation or masculinisation of the female foetus. The final common pathway of all 46,XX DSDs is excess dihydrotestosterone (DHT) or potent foreign androgen in the genital tissue during the critical period of sexual differentiation. Whereas the foetal testis is source of androgen in the male, it is the foetal adrenal that produces the DHT precursors in the female. By understanding the principles of human steroid biosynthesis, the pathogenesis of each disorder may be logically deduced, and treatment strategies are rationally constructed. In practice, however, therapies for many of these diseases are fraught with complications and caveats, and current approaches leave much room for improvement. This review discusses these diseases, their pathogenesis and approaches to therapy. We emphasise areas where improved treatments are sorely needed.

A case of Antley-Bixler syndrome caused by compound heterozygous mutations of the cytochrome P450 oxidoreductase gene.

Antley-Bixler syndrome (ABS) is a skeletal malformation syndrome primarily affecting the skull and limbs. Although causal mutations in the FGFR2 gene have been found in some patients, mutations in the electron donor enzyme P450 oxidoreductase gene (POR) have recently been found to cause ABS in other patients. In addition to skeletal malformations, POR deficiency also causes glucocorticoid deficiency and congenital adrenal hyperplasia with ambiguous genitalia in both sexes. Here, we report on a 7-month-old Korean girl with ABS and ambiguous genitalia who was confirmed by POR gene analysis. Our patient showed typical skeletal findings with brachycephaly, mid-face hypoplasia, and radiohumeral synostosis. She also had partial labial fusion and a single urogenital orifice, as well as increased 17alpha-hydroxyprogesterone levels, suggesting a 21-hydroxylase deficiency. Cortisol and DHEA-sulfate response to rapid adrenocorticotropic hormone (ACTH) stimulation was inadequate. Direct sequencing of the POR gene revealed compound heterozygous mutations (I444fsX449 and R457H). This is the first report of a Korean patient with ABS caused by POR gene mutations.