Clinical and Genetic Characteristics of Patients with Corticosterone Methyloxidase Deficiency Type 2: Novel Mutations in CYP11B2

The interpretation of immunometric, chromatographic and mass spectrometric data for steroids in diagnosis of endocrine disorders

The analysis of steroids for endocrine disorders is in transition from immunoassay of individual steroids to more specific chromatographic and mass spectrometric methods with simultaneous determination of several steroids. Gas chromatography (GC) and liquid chromatography (LC) coupled with mass spectrometry (MS) offer unrivalled analytical capability for steroid analysis. These specialist techniques were often judged to be valuable only in a research laboratory but this is no longer the case. In a urinary steroid profile up to 30 steroids are identified with concentrations and excretion rates reported in a number of ways. The assays must accommodate the wide range in steroid concentrations in biological fluids from micromolar for dehydroepiandrosterone sulphate (DHEAS) to picomolar for oestradiol and aldosterone. For plasma concentrations, panels of 5-20 steroids are reported. The profile results are complex and interpretation is a real challenge in order to inform clinicians of likely implications. Although artificial intelligence and machine learning will in time generate reports from the analysis this is a way off being adopted into clinical practice. This review offers guidance on current interpretation of the data from steroid determinations in clinical practice. Using this approach more laboratories can use the techniques to answer clinical questions and offer broader interpretation of the results so that the clinician can understand the conclusion for the steroid defect, and can be advised to program further tests if necessary and instigate treatment. The biochemistry is part of the patient workup and a clinician led multidisciplinary team discussion of the results will be required for challenging patients. The laboratory will have to consider cost implications, bearing in mind that staff costs are the highest component. GC-MS and LC-MS/MS analysis of steroids are the choices. Steroid profiling has enormous potential to improve diagnosis of adrenal disorders and should be adopted in more laboratories in favour of the cheap, non-specific immunological methods.

Rare forms of genetic paediatric adrenal insufficiency: Excluding congenital adrenal hyperplasia

Adrenal insufficiency (AI) is a severe endocrine disorder characterized by insufficient glucocorticoid (GC) and/or mineralocorticoid (MC) secretion by the adrenal glands, due to impaired adrenal function (primary adrenal insufficiency, PAI) or to insufficient adrenal stimulation by pituitary ACTH (secondary adrenal insufficiency, SAI) or tertiary adrenal insufficiency due to hypothalamic dysfunction. In this review, we describe rare genetic causes of PAI with isolated GC or combined GC and MC deficiencies and we also describe rare syndromes of isolated MC deficiency. In children, the most frequent cause of PAI is congenital adrenal hyperplasia (CAH), a group of adrenal disorders related to steroidogenic enzyme deficiencies, which will not be included in this review. Less frequently, several rare diseases can cause PAI, either affecting exclusively the adrenal glands or with systemic involvement. The diagnosis of these diseases is often challenging, due to the heterogeneity of their clinical presentation and to their rarity. Therefore, the current review aims to provide an overview on these rare genetic forms of paediatric PAI, offering a review of genetic and clinical features and a summary of diagnostic and therapeutic approaches, promoting awareness among practitioners, and favoring early diagnosis and optimal clinical management in suspect cases.

Catch-up Growth and Discontinuation of Fludrocortisone Treatment in Aldosterone Synthase Deficiency

BACKGROUND

Aldosterone synthase deficiency (ASD) caused by mutations in the CYP11B2 gene is characterized by isolated mineralocorticoid deficiency. Data are scarce regarding clinical and biochemical outcomes of the disease in the follow-up.

OBJECTIVE

Assessment of the growth and steroid profiles of patients with ASD at the time of diagnosis and after discontinuation of treatment.

DESIGN AND METHOD

Children with clinical diagnosis of ASD were included in a multicenter study. Growth and treatment characteristics were recorded. Plasma adrenal steroids were measured using liquid chromatography-mass spectrometry. Genetic diagnosis was confirmed by CYP11B2 gene sequencing and in silico analyses.

RESULTS

Sixteen patients from 12 families were included (8 females; median age at presentation: 3.1 months, range: 0.4 to 8.1). The most common symptom was poor weight gain (56.3%). Median age of onset of fludrocortisone treatment was 3.6 months (range: 0.9 to 8.3). Catch-up growth was achieved at median 2 months (range: 0.5 to 14.5) after treatment. Fludrocortisone could be stopped in 5 patients at a median age of 6.0 years (range: 2.2 to 7.6). Plasma steroid profiles revealed reduced aldosterone synthase activity both at diagnosis and after discontinuation of treatment compared to age-matched controls. We identified 6 novel (p.Y195H, c.1200 + 1G > A, p.F130L, p.E198del, c.1122-18G > A, p.I339_E343del) and 4 previously described CYP11B2 variants. The most common variant (40%) was p.T185I.

CONCLUSIONS

Fludrocortisone treatment is associated with a rapid catch-up growth and control of electrolyte imbalances in ASD. Decreased mineralocorticoid requirement over time can be explained by the development of physiological adaptation mechanisms rather than improved aldosterone synthase activity. As complete biochemical remission cannot be achieved, a long-term surveillance of these patients is required.