Turner Syndrome Mosaicism after Diagnosis of Coeliac Disease-A High Index of Clinical Suspicion Required?

The association of coeliac disease (CD) in girls with Turner syndrome (TS) is well described. There is, however, a paucity of current research describing TS in patients with known CD. We report two cases of mosaic Turner syndrome diagnosed in girls with CD who failed to achieve expected catch-up growth despite strict adherence to a gluten-free diet (GFD) and the normalisation of TGA-IgA levels. We highlight the need to consider additional diagnoses in patients with CD and ongoing faltering growth. In such patients, referral to a paediatric endocrinologist and relevant investigations, including genetic investigations, should be considered if growth remains suboptimal after one year with a GFD. First-line investigations should include thyroid function, IGF-1, cortisol, gonadotrophins, oestrogen/testosterone, prolactin, karyotype and a bone age X-ray. Clinical suspicion in this situation is key, as an early diagnosis of TS will allow timely treatment with growth hormone, inform discussion around ovarian function and allow screening for important TS associations.

Sex steroid priming for growth hormone stimulation testing in children and adolescents with short stature: A systematic review

OBJECTIVE

Growth hormone stimulation testing (GHST) is used to diagnose growth hormone deficiency (GHD) in children. As sex steroids impact on anterior pituitary function, there is concern around the efficacy of GHST in peripubertal children, where endogenous sex steroid levels are low. Sex steroid priming before GHST is thought to improve test efficacy in these children, however evidence to support its use in clinical practice is limited. In this systematic review, we addressed the following research questions: Does priming increase GH stimulation test efficacy in peripubertal children? Does priming identify those who would benefit most from treatment in terms of final height? Is there evidence for an optimal sex-steroid priming regimen?

DESIGN, PATIENTS, MEASUREMENTS

The study was registered with PROSPERO and conducted according to PRISMA guidelines. We searched Medline, Cochrane-Library, Scopus, EMBASE and Web-of-Science and included all studies that included GHST in both primed and unprimed children. A GH cut-off of 7 µg/L was used as a threshold for GHD. Study quality was assessed using the Risk-Of-Bias in Non- Randomized Studies (ROBINS-I) tool or the revised Cochrane risk-of-bias tool for Randomised trials.

RESULTS

Fifteen studies met our inclusion criteria, of which 4/15 (27%) were randomised control trials. The majority (9/15) of the studies indicated that priming increases growth hormone response upon GHST in peripubertal children, increasing test specificity. Two studies investigated final height after treatment based on the results of primed versus unprimed GHST. These results indicate that growth hormone treatment based on results of a primed GHST improve outcomes compared with treatment based on an unprimed test.

CONCLUSION

Sex-steroid priming increases the growth hormone response during GHST, resulting in fewer patients meeting the threshold required for a diagnosis of GHD. Unnecessary GH treatment may be avoided in some patients without a detrimental effect on final height. Numerous sex-steroid priming regimens have been used in clinical practice and the majority appear to be effective, but an optimal regimen has not been determined.

Type 1 diabetes incidence in Scotland between 2006 and 2019

AIMS

To describe type 1 diabetes incidence in Scotland between 2006 and 2019.

METHODS

Repeated annual cross-sectional studies of type 1 diabetes incidence were conducted. Incident cases were identified from the Scottish Care Information-Diabetes Collaboration (SCI-DC), a population-based register of people with diagnosed diabetes derived from primary and secondary care data. Mid-year population estimates for Scotland were used as the denominator to calculate annual incidence with stratification by age and sex. Joinpoint regression was used to investigate whether incidence changed during the study period. Age and sex-specific type 1 diabetes incidence over the whole time period was estimated by quintile of the Scottish Index of Multiple Deprivation (SIMD), an area-based measure, in which Q1 and Q5 denote the most and least deprived fifths of the population, respectively, with quasi-Poisson regression used to compare incidence for Q5 compared to Q1.

RESULTS

The median (IQR) age of the study population of 14,564 individuals with incident type 1 diabetes was 24.1 (12.3-42.4) years, 56% were men, 23% were in Q1 and 16% were in Q5. Incidence of T1DM was higher in men than women overall (at around 22 and 17 per 100,000, respectively) and in under 15 year olds (approximately 40 per 100,000 in both sexes) than other age groups and was similar across the study period in all strata. There was an inverse association between socio-economic status and type 1 diabetes incidence for 15-29, 30-49 and 50+ year olds [incidence rate ratio (IRR) for Q5 compared to Q1; IRR (95% CI) 0.52 (0.47-0.58), 0.68 (0.61-0.76) and 0.53(0.46-0.61), respectively] but not for under 15 year olds [1.02 (0.92-1.12)].

CONCLUSION

Incidence of type 1 diabetes varies by age, sex and socio-economic status and has remained approximately stable from 2006 to 2019 in Scotland.

A New Multisystem Disorder Caused by the Gαs Mutation p.F376V

CONTEXT

The α subunit of the stimulatory G protein (Gαs) links numerous receptors to adenylyl cyclase. Gαs, encoded by GNAS, is expressed predominantly from the maternal allele in certain tissues. Thus, maternal heterozygous loss-of-function mutations cause hormonal resistance, as in pseudohypoparathyroidism type Ia, whereas somatic gain-of-function mutations cause hormone-independent endocrine stimulation, as in McCune-Albright syndrome.

OBJECTIVE

We report two unrelated boys presenting with a new combination of clinical findings that suggest both gain and loss of Gαs function.

DESIGN AND SETTING

Clinical features were studied and sequencing of GNAS was performed. Signaling capacities of wild-type and mutant Gαs were determined in the presence of different G protein-coupled receptors (GPCRs) under basal and agonist-stimulated conditions.

RESULTS

Both unrelated patients presented with unexplained hyponatremia in infancy, followed by severe early onset gonadotrophin-independent precocious puberty and skeletal abnormalities. An identical heterozygous de novo variant (c.1136T>G; p.F376V) was found on the maternal GNAS allele in both patients; this resulted in a clinical phenotype that differed from known Gαs-related diseases and suggested gain of function at the vasopressin 2 receptor (V2R) and lutropin/choriogonadotropin receptor (LHCGR), yet increased serum PTH concentrations indicative of impaired proximal tubular PTH1 receptor (PTH1R) function. In vitro studies demonstrated that Gαs-F376V enhanced ligand-independent signaling at the PTH1R, LHCGR, and V2R and, at the same time, blunted ligand-dependent responses. Structural homology modeling suggested mutation-induced modifications at the C-terminal α5 helix of Gαs that are relevant for interaction with GPCRs and signal transduction.

CONCLUSIONS

The Gαs p.F376V mutation causes a previously unrecognized multisystem disorder.

Partial diazoxide responsiveness in a neonate with hyperinsulinism due to homozygous ABCC8 mutation

We report a case of partial diazoxide responsiveness in a child with severe congenital hyperinsulinaemic hypoglycaemia (CHI) due to a homozygous ABCC8 mutation. A term baby, with birth weight 3.8 kg, born to consanguineous parents presented on day 1 of life with hypoglycaemia. Hypoglycaemia screen confirmed CHI. Diazoxide was commenced on day 7 due to ongoing elevated glucose requirements (15 mg/kg/min), but despite escalation to a maximum dose (15 mg/kg/day), intravenous (i.v.) glucose requirement remained high (13 mg/kg/min). Genetic testing demonstrated a homozygous ABCC8 splicing mutation (c.2041-1G>C), consistent with a diffuse form of CHI. Diazoxide treatment was therefore stopped and subcutaneous (s.c.) octreotide infusion commenced. Despite this, s.c. glucagon and i.v. glucose were required to prevent hypoglycaemia. A trial of sirolimus and near-total pancreatectomy were considered, however due to the significant morbidity potentially associated with these, a further trial of diazoxide was commenced at 1.5 months of age. At a dose of 10 mg/kg/day of diazoxide and 40 µg/kg/day of octreotide, both i.v. glucose and s.c. glucagon were stopped as normoglycaemia was achieved. CHI due to homozygous ABCC8 mutation poses management difficulties if the somatostatin analogue octreotide is insufficient to prevent hypoglycaemia. Diazoxide unresponsiveness is often thought to be a hallmark of recessively inherited ABCC8 mutations. This patient was initially thought to be non-responsive, but this case highlights that a further trial of diazoxide is warranted, where other available treatments are associated with significant risk of morbidity. Learning points: Homozygous ABCC8 mutations are commonly thought to cause diazoxide non-responsive hyperinsulinaemic hypoglycaemia. This case highlights that partial diazoxide responsiveness in homozygous ABCC8 mutations may be present. Trial of diazoxide treatment in combination with octreotide is warranted prior to considering alternative treatments, such as sirolimus or near-total pancreatectomy, which are associated with more significant side effects.