Search

P450 oxidoreductase (POR) deficiency is an autosomal recessive disorder of steroidogenesis with multiple clinical manifestations. POR is the electron donor for all microsomal P450 enzymes, including the three steroidogenic enzymes P450c17 (17α-hydroxylase/17,20-lyase), P450c21 (21-hydroxylase), and P450aro (aromatase). Since the first description of POR mutations in 2004, about 50 patients have been reported. Serum steroid profiles indicate partial deficiencies in 21-hydroxylase, 17α-hydroxylase and 17,20-lyase. The 17-OH progesterone levels are elevated, as in 21-hydroxylase deficiency, while androgen levels are low; cortisol may be normal but is poorly responsive to adrenocorticotropic hormone. Most patients also have associated skeletal malfor- mations (craniosynostosis, radio-ulnar synostosis, midface hypoplasia, bowed femora) termed Antley-Bixler syndrome. Antley-Bixler syndrome with normal steroidogenesis is caused by autosomal dominant gain-of-function mutations in fibroblast growth factor receptor 2. Males with POR deficiency are often undervirilized, while females can be virilized. The prognosis for patients with POR deficiency appears to depend on the severity of the bony malformations and their timely treatment. The potential impact of POR mutations on drug metabolism by other hepatic P450 enzymes requires further investigation. Given the varied physical and biochemical phenotype of POR deficiency and the risk of adrenal insufficiency, clinicians should be alert to this potential diagnosis. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

It has been shown that growth hormone (GH) and insulin-like growth factor-1 (IGF1) enhance steroidogenesis responsiveness to ACTH in cultured adrenal cells. To investigate the GH effect on adrenal steroidogenesis in non-GH-deficient subjects, we studied 9 girls with Turner syndrome (chronological age 5.5–7.2 years; bone age 5–7 years). In all subjects an ACTH test (Synacthen depot, 0.25 mg i.v. with blood samples at 0 and 60 min) was performed basally at 8–9 a.m. and 6 months after GH therapy (1 IU/kg/week). 17-Hydroxypregnenolone (17PGN), 17-hydroxyprogesterone (17OHP), dehydroepiandrosterone (DHA), its sulfate (DHA-S), androstenedione and cortisol were evaluated by radioimmunoassay. Two groups of normal girls were selected as controls: group A age-matched the patients at the start of the study, and group B age-matched the patients at the end of the study. The responsiveness of each hormone to ACTH was expressed as the difference between stimulated and basal values. A p value of < 0.01 was considered to indicate significance. There were no significant differences between pre- and posttreatment basal values of 17PGN, 17OHP, DHA, androstenedione and cortisol in the Turner syndrome patients, whereas a significant increase was observed for basal DHA-S (1.57 ± 0.31; 1.89 ± 0.43 µmol/l, p < 0.01). Comparison of increments before and after GH treatment showed a significant increase in responsiveness to ACTH after GH therapy DHA (p < 0.01). The increase in 17PGN was evident (p < 0.02), but the established significant p value was not reached. No differences for 17OHP, androstenedione and cortisol were found. The stimulated 17PGN/17OHP ratio was significantly higher (p < 0.01) after GH, whereas the 17OHP/androstenedione ratio was considerably lower, but the p value was < 0.02. No differences between pretreatment values with the control group androstenedione was found, whereas basal and stimulated posttreatment values of DHA and stimulated values of 17PGN were higher in patients after GH therapy than in control group B. No differences between the 2 control groups were found. In conclusion our study showed that adrenal steroid responsiveness to ACTH increases in Turner syndrome after long-term treatment with high GH doses. An increase in the number of ACTH adrenal receptors and/or a modulation of enzyme activities may be suggested. The positive or negative pharmacological implications of these data remain to be determined especially when taking into consideration the wide use of GH therapy in non-GH-deficient subjects. [ABSTRACT FROM AUTHOR]