Elucidating the underlying molecular pathogenesis of NR3C2 mutants causing autosomal dominant pseudohypoaldosteronism type 1.

CONTEXT: Pseudohypoaldosteronism type 1 (PHA1) is a rare salt-wasting syndrome. Mutations in the NR3C2 gene coding for the mineralocorticoid receptor (MR) cause autosomal dominant PHA1. OBJECTIVE: Our objective was to reveal the cause of renal salt loss in six PHA1 patients and analyze the mutants' functional impact on MR function. DESIGN: Our study included the following: clinical and hormonal characterization of the patients' phenotype, analysis of the NR3C2 gene, determination of receptor affinities to aldosterone and the transcriptional activation abilities of the MR mutants, investigation of subcellular translocation using fluorescence-labeled MR, and studying changes in mutant receptor conformation with proteolysis experiments and three-dimensional modeling. RESULTS: Six heterozygous NR3C2 mutations were detected. One frameshift mutation (c.1131dupT) has been reported previously. The second frameshift mutation (c.2871dupC), which has only recently been reported by our group, showed no aldosterone binding and no transactivation because of a major change in receptor conformation. Two novel nonsense mutations generate a truncated receptor protein. Two missense mutations differently affect MR function. S818L was reported recently without complete in vitro data. S818L does not bind aldosterone or activate transcription or translocate into the nucleus. A major displacement of several residues involved in aldosterone binding was PHA1 causing. The novel E972G mutation showed a significantly lower ligand-binding affinity and only 9% of wild-type transcriptional activity caused by major changes in receptor conformation. CONCLUSIONS: Our data on six mutations extend the spectrum of PHA1-causing NR3C2 gene mutations. Studying naturally occurring mutants helps to clarify their pathogenicity and to identify crucial residues for MR structure and function.

Management of congenital adrenal hyperplasia: results of the ESPE questionnaire.

The management of children and adolescents with congenital adrenal hyperplasia (CAH) remains difficult. To assess the current European practice in diagnosis and management of CAH, an ESPE (European Society for Paediatric Endocrinology) survey was circulated in 2000/2001. The questionnaire was answered by 34% of ESPE members, representing 125 institutions which cared for 6,553 CAH patients. Paediatric endocrinologists, surgeons, gynaecologists, geneticists, and psychologists are involved in the immediate care of the CAH neonate and his family. 44% of centres take part in neonatal screening programmes. In families at risk, prenatal dexamethasone therapy is started at a median gestational age of 6 weeks in a median dose of 20 microg/kg/day. 53% reported maternal adverse events, 8% observed adverse fetal events. Regarding feminizing surgery, 33% reported simultaneous clitoric reduction and vaginoplasty during infancy. However, clitoridectomy is still reported by 13% of centres, and vaginal dilatations have been performed by 27%. Although 71% of female CAH patients with psychosexual problems, only 17% undertake routine psychodiagnostics and counselling. Hydrocortisone is the substance used for the treatment of CAH during growth in 84%; the median dose (mg/m(2)/day) is 17.5 in infants, 15 in children and adolescents, and 13.75 in adults. The glucocorticoid dose is increased two- to sixfold during intercurrent stress. Mineralocorticoid is administered in cases of clinically manifest salt wasting and of elevated plasma renin activity, to decrease high glucocorticoid doses, or according to genotype. All participating ESPE members feel the need for further improvement in prenatal diagnosis and treatment, compliance during puberty, screening programmes, psychological aspects, and corrective surgery.