Endocrine Abstracts

Background: The standard dose Synacthen test (SDST) is commonly used to identify glucocorticoid deficiency. A subnormal SDST in young infants raises the possibility of adrenal insufficiency (AI) due to pathology such as congenital adrenal hyperplasia (CAH). A physiological delay in maturation of adrenal glucocorticoid secretion may be another explanation especially in asymptomatic infants with a transiently subnormal SDST.Aims: To review the diagnoses an...

Loss-of-function mutations of the calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR), result in familial hypocalciuric hypercalcaemia (FHH), a disorder of extracellular calcium homeostasis affecting the parathyroids and kidneys. However, around 35% of FHH patients do not have CaSR mutations. A form of FHH, designated FHH2, has been mapped to chromosome 19p. The GNA11 gene, encoding G-protein α11 (Gα11), a component of the CaSR sign...

Dent’s disease, due to mutations in the chloride/proton antiporter, CLC-5, represents one form of familial hypophosphataemic rickets. Dent’s disease patients also have: low-molecular-weight-proteinuria; hypercalciuria with nephrolithiasis and renal failure; and urinary loss of parathyroid hormone and vitamin D-binding protein, due to defective receptor-mediated endocytosis within the renal proximal tubule. However, there is variability in these clinical phenotypes su...

The calcium-sensing receptor (CaSR) is a G protein-coupled receptor with an extracellular bilobed venus flytrap domain (VFTD) predicted to contain five calcium-binding sites. The major site for calcium-binding is comprised of amino acid residues that line the cleft between the two lobes of the VFTD. We investigated the structure-function relationships of VFTD CaSR mutations identified in patients with familial hypocalciuric hypercalcaemia (FHH), neonatal severe primary hyperpa...

Kyphosis and scoliosis are common spinal disorders that lead to significant morbidity in childhood, adolescence and adulthood. Familial and twin studies have implicated a genetic involvement, although the causative genes remain to be identified. To facilitate these studies, we investigated 12-week-old progeny of mice treated with the chemical mutagen N-ethyl-N-nitrosourea (ENU) using phenotypic assessments that included dysmorphology, radiography and dual-energy ...

Receptor-mediated endocytosis (RME), involving megalin and cubilin, mediates renal proximal-tubular reabsorption of glucose, proteins and hormones including insulin, parathyroid-hormone and vitamin D. RME disruption occurs in Dent’s disease patients with mutations of the chloride/proton antiporter, CLC-5, who suffer from low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis and renal failure. To further investigate the RME role of CLC-5 we established conditio...

Multiple endocrine neoplasia type 1 (MEN1) is characterised by the combined occurrence of pituitary, pancreatic and parathyroid tumours. The MEN1 gene encodes a 610-amino acid tumour suppressor, menin, and MEN1-associated tumours show loss of heterozygosity. This indicates that replacement of the wild-type MEN1 gene may inhibit tumourigenesis. We have previously demonstrated that a recombinant adenoviral vector could be safely injected directly into pituit...

Activating mutations of the calcium sensing receptor (CaSR) result in autosomal dominant hypocalcaemia with hypercalciuria (ADHH), in which patients may also suffer from polyuria, polydipsia, nephrocalcinosis, renal impairment, and ectopic calcification. A mouse model, Nuf, with an activating Leu723Gln CaSR mutation has been reported to develop the features of ADHH as well as cataracts that consist of dot nuclear opacities, which have not been described in ADHH patients...

The G-protein coupled calcium-sensing-receptor (CaSR) regulates calcium homeostasis and inactivating mutations result in familial hypocalciuric hypercalcaemia (FHH), whilst activating mutations result in autosomal dominant hypocalcaemia with hypercalciuria (ADHH). Allosteric CaSR modulators consist of: calcimimetics, which activate the CaSR e.g. Cinacalcet, that is used to treat the hypercalcaemia of chronic renal failure and metastatic parathyroid carcinoma; and calcilytics e...

(This poster is based on OC24)...