Corticosterone methyl oxidase type II (CMO II) deficiency: biochemical approach to diagnosis

Steroid Metabolome Analysis in Disorders of Adrenal Steroid Biosynthesis and Metabolism

Steroid biosynthesis and metabolism are reflected by the serum steroid metabolome and, in even more detail, by the 24-hour urine steroid metabolome, which can provide unique insights into alterations of steroid flow and output indicative of underlying conditions. Mass spectrometry-based steroid metabolome profiling has allowed for the identification of unique multisteroid signatures associated with disorders of steroid biosynthesis and metabolism that can be used for personalized approaches to diagnosis, differential diagnosis, and prognostic prediction. Additionally, steroid metabolome analysis has been used successfully as a discovery tool, for the identification of novel steroidogenic disorders and pathways as well as revealing insights into the pathophysiology of adrenal disease. Increased availability and technological advances in mass spectrometry-based methodologies have refocused attention on steroid metabolome profiling and facilitated the development of high-throughput steroid profiling methods soon to reach clinical practice. Furthermore, steroid metabolomics, the combination of mass spectrometry-based steroid analysis with machine learning-based approaches, has facilitated the development of powerful customized diagnostic approaches. In this review, we provide a comprehensive up-to-date overview of the utility of steroid metabolome analysis for the diagnosis and management of inborn disorders of steroidogenesis and autonomous adrenal steroid excess in the context of adrenal tumors.

A compound heterozygote case of type II aldosterone synthase deficiency

An infant with failure to thrive, persistent hyponatremia and episodic vomiting and diarrhea was admitted to hospital at 9 months of age, and the diagnosis of type II aldosterone synthase deficiency was confirmed by plasma and urinary steroid determinations. The entire coding sequence of the aldosterone synthase gene (CYP11B2) was determined (both strands) in the affected infant, an unaffected sibling, and both parents. An exon 3 mutation (C554T, leading to amino acid T185I) was found in the father and both siblings, and an exon 9 mutation (A1492G, leading to T498A) was found in the affected infant and the mother. Expression of the mutant sequences in COS cells showed steroidogenic patterns typical of aldosterone synthase type II deficiency, including very low levels of aldosterone synthesis (< or =0.5% of wild-type enzyme) consistent with the low aldosterone levels in the patient's plasma. Both mutations in this compound heterozygote localize to the beta 3-sheet in the cytochrome P450 enzyme structure, as does the previously characterized R181W mutation. This region of the enzyme is not part of the putative structural core, but mutations to this region suggest that it is important for conferring the unique ability of aldosterone synthase to catalyze efficient oxygenation of the C(18) carbon of steroid substrates.

CYP11 beta 1 (11-beta-hydroxylase) deficiency in congenital adrenal hyperplasia

OBJECTIVE

To review experience of CYP11 beta 1 deficiency (previously known as 11 beta-hydroxylase) at the Royal Children's Hospital, Melbourne, Victoria.

METHODOLOGY

A retrospective case review was conducted from 1974 to 1995 with five cases identified.

RESULTS

Age of presentation ranged from 1 day to 7 years. Presentation was with ambiguous genitalia at birth (two females), simple virilization (two males) and suspected early puberty in mid childhood (one female). Associated clinical features were hypertension (three cases) and tail stature with markedly advanced bone age (four cases). Biochemical abnormalities consistent with CYP11 beta 1-deficiency were elevated urinary tetrahydro-11-deoxycortisol (n = 5) and elevated serum 11-deoxycortisol (n = 3). Additional abnormalities were elevated 17-hydroxyprogesterone (n = 3), elevated androstenedione (n = 4) and elevated dehydroepiandrosterone sulphate (n = 4). The clinical features and investigations suggested CYP11 beta 1-classical deficiency in four patients and CYP11 beta 1-non-classical deficiency in one patient.

CONCLUSIONS

The five cases of CYP11 beta 1-deficiency demonstrate a spectrum of clinical abnormalities, with diagnostic difficulties in two cases and delayed presentation in three cases. Prompt diagnosis of CYP11 beta 1-deficiency is facilitated greatly by the availability of a gas chromatography-mass spectrometry instrument and is essential to avoid the long-term effects of hypertension and hyperandrogenism.

Endocrinology and auxology of sibships with non-classical congenital adrenal hyperplasia

The symptoms, auxological characteristics, and stimulated 17-hydroxyprogesterone (17-OHP) concentrations in a group of patients with non-classical 21-hydroxylase deficiency (NCCAH) were compared with those of their siblings. Ten index cases consisting of nine females and one male patient aged 3-33 years and 16 siblings were studied. In the sibling group five subjects were slightly virilised and of these, two females were found to have NCCAH according to their stimulated 17-OHP concentrations. The remaining nine siblings, who were not virilised, all had normal stimulated 17-OHP concentrations. Among the total NCCAH group (index cases and affected siblings) eight patients had the diagnosis made within two years of the onset of symptoms. In four patients diagnosis was delayed until adulthood. In seven patients investigated, bone age was significantly increased before treatment. The mean height and body mass index Z scores of the affected patients as a total group or when divided according to skeletal maturity were not significantly different from either the normal mean or from their unaffected siblings. Virilised siblings of patients with NCCAH should have stimulated 17-OHP levels measured to exclude the disease. Patients with NCCAH do not appear to be at risk of short adult stature despite increased bone age in childhood.