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The most potent corticosteroids are 11β-hydroxylated compounds. In humans, two cytochrome P450 isoenzymes with 11β-hydroxylase activity, catalysing the biosynthesis of cortisol and aldosterone, are present in the adrenal cortex. CYP11B1, the gene encoding 11β-hydroxylase (P450c11), is expressed on high levels in the zona fasciculata and is regulated by ACTH. CYP11B2, the gene encoding aldosterone synthase (P450c11Aldo), is expressed in the zona glomerulosa under primary control of the renin-angiotensin system. Aldosterone synthase has 11β-hydroxylase activity as well as 18-hydroxylase activity and 18-oxidase activity. The substrate for CYP11B2 is 11-deoxycorticosterone, that of CYP11B1 is 11-deoxycortisol. Mutations in CYP11B1 cause congenital adrenal hyperplasia (CAH) due to 11β-hydroxylase deficiency. This disorder is characterized by androgen excess and hypertension. Mutations in CYP11B2 cause congenital hypoaldosteronism (aldosterone synthase deficiency) which is characterized by life-threatening salt loss, failure to thrive, hyponatraemia and hyperkalaemia in early infancy. Both disorders have an autosomal recessive inheritance. Classical and nonclassical forms of 11β-hydroxylase deficiency can be distinguished. Studies in heterozygotes for classical 11β-hydroxylase deficiency show inconsistent results with no or only mild hormonal abnormalities (elevated plasma levels of 11-deoxycortisol after ACTH stimulation). In infants with congenital hypoaldosteronism, a comparable frequency of 18-hydroxylase deficiency (aldosterone synthase deficiency type I) and of 18-oxidase deficiency (aldosterone synthase deficiency type II) can be found. Molecular genetic studies of the CYP11B1 and CYP11B2 genes in 11β-hydroxylase deficiency or aldosterone synthase deficiency have led to the identification of several mutations. Transfection experiments showed loss of enzyme activity in vitro. In some of the patients with 18-oxidase deficiency (aldosterone synthase deficiency type II) no mutations in the CYP11B2 gene were identified. Refined methods for steroid determination are the basis for the diagnosis of inborn errors of steroidogenesis. Molecular genetic studies are complementary; on the one hand, they have practical importance for the prenatal diagnosis of virilizing CAH forms and on the other hand, they are of theoretical importance in terms of our understanding of the functioning of cytochrome P450 enzymes.

ABSTRACT. As part of an ongoing international multicentre study, 19 children (14 girls, 5 boys) with central precocious puberty (CPP) were treated with a slow‐release gonadotrophin‐releasing hormone (GnRH) agonist, triptorelin, for 4 years. After 3 years of treatment, height velocity stabilized at 4.0 cm/year. Predicted adult height (mean ± SD) increased from 158.9 ± 6.8 to 164.9 ± 6.6 cm in girls (n = 14, p < 0.01), and from 174.4 ± 18.5 to 184.3 ± 17.1 cm in boys (n = 4, p < 0.05). In 12 additional girls who had started the multicentre study but discontinued triptorelin treatment after 2.2 ± 0.5 years, menses started 9.8 ± 3.7 months after cessation of treatment in all but one patient. Height velocity increased over the first 6 months after discontinuation of treatment, from 3.6 ± 0.1 to 5.4 ± 2.5 cm/year, and remained higher than pretreatment values in the second 6 months, but decreased subsequently. Bone maturation increased, and no significant improvement in predicted adult height was observed. For auxological reasons, therefore, it may be advisable to continue triptorelin treatment for as long as possible. Concomitant growth hormone (GH) therapy was initiated in three girls with CPP with height velocities of 3.2–3.6 cm/year after 3 years of treatment with triptorelin and predicted adult heights of less than the third centile for Dutch girls. Prior to the administration of GH, all patients had subnormal 24‐hour GH profiles and GH responses to arginine provocation. GH treatment increased height velocity markedly in all girls, and improved predicted adult height. It is concluded that triptorelin therapy improves predicted adult height. In children with CPP and genetic short stature, with a markedly decreased height velocity during triptorelin therapy, concomitant administration of a GnRH agonist and GH may have advantages. Further extensive studies are required.

Patients with CAH and complete virilization have a high risk of being diagnosed late. There are major problems and uncertainties of the patients' families and the treating physicians concerning gender assignment. Gender identity is disturbed in some patients. In addition, multiple surgical procedures are necessary and short stature as well as central precocious puberty might be important to avoid late sequelae. While some surgical interventions are probably unavoidable, most of these issues could be resolved with an early diagnosis. Thus, especially for these patients, a neonatal screening programme for CAH would be of paramount importance.

The first child of consanguineous parents presented with failure to thrive and feeding problems at age 6 weeks. Important laboratory findings were low plasma sodium and elevated potassium and renin. Salt wasting was caused by an enzymatic defect in the terminal aldosterone biosynthesis. The biochemical diagnosis of corticosterone methyloxidase (CMO) deficiency type II was established on the basis of plasma multisteroid analysis, showing a pathologic increase of 18-OH-corticosterone/aldosterone ratio. Sequence analysis of the CYP11B2 gene which encodes aldosterone synthase (P450c11Aldo), the enzyme required for the terminal steps in aldosterone biosynthesis, revealed a hitherto undescribed homozygous deletion of codon 173. CYP11B2 is polymorphic at this position, encoding arginine or lysine. Both parents were heterozygous carriers of the mutation. Amino acid residue 173 in P450c11Aldo is positioned in α-helix D. We presume that the secondary structure of the enzyme is changed by the single amino acid deletion. This report describes a novel mutation in the CYP11B2 gene, the third known mutation associated with CMO deficiency type II.

Children born small for gestational age may demonstrate continued growth retardation, resulting in persistent short stature. In the majority of the cases, this is linked with abnormal growth hormone secretion and also abnormal insulin-like growth factor levels. This review discusses the treatment of such children with recombinant human growth hormone. It illustrates the importance of starting therapy early, the dose-dependent response, and the advantages of continuous therapy and describes safety considerations.

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