Frequency of AIP gene mutations in young patients with acromegaly: a registry-based study

CONTEXT

Familial and sporadic GH-secreting pituitary adenomas are associated with mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene. Patients with an AIP mutation (AIPmut) tend to have more aggressive tumors occurring at a younger age.

OBJECTIVE

The objective of the study was to investigate the frequency of AIPmut in patients diagnosed at 30 years of age or younger.

DESIGN

The German Acromegaly Registry database (1795 patients in 58 centers) was screened for patients diagnosed with acromegaly at 30 years of age or younger (329 patients). Sixteen centers participated and 91 patients consented to AIPmut analysis.

INTERVENTION

DNA was analyzed by direct sequencing and multiplex ligation dependent probe amplification Main outcome Measures: The number of patients with AIPmut was measured.

RESULTS

Five patients had either a mutation (c.490C>T, c.844C>T, and c.911G>A, three males) or gross deletions of exons 1 and 2 of the AIP gene (n = 2, one female). The overall frequency of an AIPmut was 5.5%, and 2.3% or 2.4% in patients with an apparently sporadic adenoma or macroadenoma, respectively. By contrast, three of four patients (75%) with a positive family history were tested positive for an AIPmut. Except for a positive family history, there were no significant differences between patients with and without an AIPmut.

CONCLUSIONS

The frequency of AIPmut in this registry-based cohort of young patients with acromegaly is lower than previously reported. Patients with a positive family history should be tested for an AIPmut, whereas young patients without an apparent family history should be screened, depending on the individual cost to benefit ratio.

[Quality of life of young adults after a growth hormone therapy with childhood onset]

INTRODUCTION

Little is known about the health-related quality of life of young adults with childhood onset idiopathic growth hormone deficiency or neurosecretory dysfunction of growth hormone secretion, who have been treated with recombinant human growth hormone (GH).

METHODS

Patients were diagnosed and treated with human growth hormone at the University Children´s Hospital in Erlangen (n=85). The data of both groups were merged for analysis, because no difference between idiopathic growth hormone deficiency and neurosecretory dysfunction of growth hormone secretion in auxological. Data were found. Health-related quality of life was cross- sectionally assessed after the end of growth hormone therapy with the Short Form-36 Health Survey and the Nottingham Health Profiles for which population based norm data are available.

RESULTS

At the time of the survey, the patients (53 m, 32 f) were 23.5 ± 4.6 years old. At start of GH therapy, age was 10.5 ± 2.8 and at the end 16.3 ± 1,4 years. At start, height SDS was -3.20 ± 1.06. GH dose was 0,026 ± 0,012 mg/kg/d (daily s. c.-injections). The increase in height SDS after the end of GH therapy was 1.69 ± 1.22.  Compared to the reference population, patients reported significantly lower scores on the scales energy level, vitality, social functioning, indicating a greater social isolation, a stronger emotional reaction, an increased loss of mobility and a worse psychological state.

CONCLUSION

Young adults report specific impairments after completion of GH therapy.

A homozygous CaSR mutation causing a FHH phenotype completely masked by vitamin D deficiency presenting as rickets

CONTEXT

Heterozygous inactivating calcium-sensing receptor (CaSR) mutations lead to familial hypocalciuric hypercalcemia (FHH), whereas homozygous mutations usually cause neonatal severe hyperparathyroidism.

OBJECTIVE

The objective of the study was to investigate the pathophysiological mechanisms of a homozygous inactivating CaSR mutation identified in a 16-year-old female.

DESIGN

Clinical, biochemical, and genetic analyses of the index patient and her family were performed. Functional capacity of CaSRQ459R and CaSR mutants causing FHH (Q27R, P39A, S417C) or neonatal severe hyperparathyroidism (W718X) was assessed. Activation of the cytosolic calcium pathway and inhibition of PTH-induced cAMP signaling were measured.

RESULTS

A 16-year-old girl presented with adolescent rickets, vitamin D deficiency, and secondary hyperparathyroidism. Vitamin D treatment unmasked features resembling FHH, and genetic testing revealed a homozygous CaSRQ459R mutation. Two apparently healthy siblings were homozygous for CaSRQ459R and had asymptomatic hypercalcemia and hypocalciuria. The CaSRQ459R mutation leads to mild functional inactivation in vitro, which explains the FHH-like phenotype in homozygous family members and the grossly exaggerated PTH response to vitamin D deficiency in the index case. The patient's parents and two other siblings were heterozygous, had normal serum calcium and PTH, but had marked hypocalciuria, which appeared to be associated with impaired in vitro activation of the calcium signaling pathway by CaSRQ459R. The Q459R mutation responded well to calcimimetic treatment in vitro.

CONCLUSION

CaSR mutations causing mild functional impairment can lead to FHH, even in homozygous patients. The skeletal deformities in the index case were mainly due to severe vitamin D deficiency, and the CaSR mutation did not appear to have played a major independent role in the skeletal phenotype.

Molecular and functional properties of densely and sparsely granulated GH-producing pituitary adenomas

OBJECTIVE

GH-producing pituitary adenomas display two distinct morphological patterns of cytoplasmic GH-containing secretory granules, namely the densely and sparsely granulated somatotroph adenoma subtype. It is unknown whether these morphological variants reflect distinct pathophysiological entities at the molecular level.

METHODS

In 28 GH-producing adenoma tissues from a consecutive set of patients undergoing pituitary surgery for acromegaly, we studied the GH granulation pattern, the expression of somatostatin receptor subtypes (SSTR) as well as the calcium, cAMP and ZAC1 pathways in primary adenoma cell cultures.

RESULTS

The expression of GSP oncogene was similar between densely and sparsely granulated somatotroph adenoma cells. There were no differences in the calcium, cAMP and ZAC1 pathways as well as in their regulation by SSTR agonists. SSTR2 was exclusively expressed in densely but not in sparsely granulated tumours (membrane expression 86 vs 0%; cytoplasmic expression 67 vs 0%). By contrast, expression of SSTR5 was only found in sparsely but not in densely granulated somatotroph adenomas (membrane expression 29 vs 0%; cytoplasmic expression 57 vs 0%).

CONCLUSIONS

Our results indicate that different granulation patterns in GH-producing adenomas do not reflect differences in pathways and factors pivotal for somatotroph differentiation and function. In vitro, the vast majority of both densely and sparsely granulated tumour cells were responsive to SSTR activation at the molecular level. Sparsely granulated adenomas lacking SSTR2, but expressing SSTR5, might be responsive to novel SSTR agonists with increased affinity to SSTR5.

Cystic fibrosis-related diabetes compared with type 1 and type 2 diabetes in adults

BACKGROUND

With increasing life expectancy of patients with cystic fibrosis (CF), secondary diabetes becomes more prevalent. It appears to be the most common co-morbidity in persons with cystic fibrosis. Therefore, the objective of our study was to describe characteristics of cystic fibrosis-related diabetes compared with type 1 and 2 diabetes (T1DM/T2DM) in adults.

METHODS

Data from 218 436 patients >18 years with cystic fibrosis (n = 401), T1DM (n = 32,409) or T2DM (n = 185 626) in the multicenter Diabetes-Patienten-Verlaufsdokumentation or prospective documentation of diabetes patients registry were analysed.

RESULTS

Diabetes onset [median (interquartile range)] in cystic fibrosis [18.70 (15.50-25.30) years] was between T1DM [16.40 (10.50-31.80) years] and T2DM [58.50 (48.80-68.00) years], with female preponderance. Body mass index (BMI) and glycosylated haemoglobin (HbA1c ) were lowest (19.6 [18.1-21.5] kg/m(2) )/50 mmol/mol (6.73%) versus T1DM (24.4 [22.1-27.4])/62 mmol/mol (7.83%) vs. T2DM (29.6 [26.1-33.9])/54 mmol/mol (7.06%); all p < 0.01. A total of 78.6% of cystic fibrosis patients with diabetes received insulin. Insulin dose (0.74 IE/kg bodyweight) was not significantly different from T1DM (0.73) and T2DM (0.76). Frequency of vascular complications, adjusted for confounding effects, across the groups was different: Hypertension (CFRD 16.1% vs. T1DM 24.0% vs. T2DM 32.2%; all p < 0.01), retinopathy (CFRD 10.7% vs. T1DM 10.4% vs. T2DM 10.5%, not significant), nephropathy (CFRD 25.2% vs. T1DM 17.2% vs. T2DM 24.7%; only T1DM/T2DM; p < 0.01).

CONCLUSION

CFRD is a uniquely complex entity with clear differences from T1DM and T2DM in adults.

Activation of the Ca²+-sensing receptor induces deposition of tight junction components to the epithelial cell plasma membrane

The Ca(2+)-sensing receptor (CaSR) belongs to the G-protein-coupled receptor superfamily and plays essential roles in divalent ion homeostasis and cell differentiation. Because extracellular Ca(2+) is essential for the development of stable epithelial tight junctions (TJs), we hypothesized that the CaSR participates in regulating TJ assembly. We first assessed the expression of the CaSR in Madin-Darby canine kidney (MDCK) cells at steady state and following manipulations that modulate TJ assembly. Next, we examined the effects of CaSR agonists and antagonists on TJ assembly. Immunofluorescence studies indicate that endogenous CaSR is located at the basolateral pole of MDCK cells. Stable transfection of human CaSR in MDCK cells further reveals that this protein co-distributes with β-catenin on the basolateral membrane. Switching MDCK cells from low-Ca(2+) medium to medium containing a normal Ca(2+) concentration significantly increases CaSR expression at both the mRNA and protein levels. Exposure of MDCK cells maintained in low-Ca(2+) conditions to the CaSR agonists neomycin, Gd(3+) or R-568 causes the transient relocation of the tight junction components ZO-1 and occludin to sites of cell-cell contact, while inducing no significant changes in the expression of mRNAs encoding junction-associated proteins. Stimulation of CaSR also increases the interaction between ZO-1 and the F-actin-binding protein I-afadin. This effect does not involve activation of the AMP-activated protein kinase. By contrast, CaSR inhibition by NPS-2143 significantly decreases interaction of ZO-1 with I-afadin and reduces deposition of ZO-1 at the cell surface following a Ca(2+) switch from 5 µM to 200 µM [Ca(2+)]e. Pre-exposure of MDCK cells to the cell-permeant Ca(2+) chelator BAPTA-AM, similarly prevents TJ assembly caused by CaSR activation. Finally, stable transfection of MDCK cells with a cDNA encoding a human disease-associated gain-of-function mutant form of the CaSR increases the transepithelial electrical resistance of these cells in comparison to expression of the wild-type human CaSR. These observations suggest that the CaSR participates in regulating TJ assembly.

GLP-1 analogues as a new treatment option for hypothalamic obesity in adults: report of nine cases

BACKGROUND

Patients with hypothalamic pathology often develop morbid obesity, causing severe metabolic alterations resulting in increased morbidity and mortality. Glucagon-like peptide-1 (GLP-1) analogues improve glycaemic control in type 2 diabetic patients and cause weight loss in obese patients by yet unknown mechanisms. Here we tested whether GLP-1 analogues were also effective in the treatment of obesity and associated metabolic alterations in patients with hypothalamic disease.

METHODS

Nine patients (eight with type 2 diabetes mellitus) with moderate to severe hypothalamic obesity were treated with GLP-1 analogues for up to 51 months. Body weight, homeostasis model assessment - insulin resistance (HOMA-IR), HbA1c and lipids were assessed.

RESULTS

Eight patients experienced substantial weight loss (-13.1±5.1 kg (range -9 to -22)). Insulin resistance (HOMA-IR -3.2±3.5 (range -9.1 to 0.8)) and HbA1c values (-1.3±1.4% (range -4.5 to 0.0)) improved under treatment (24.3±18.9 months (range 6 to 51)). Five patients reported increased satiation in response to the treatment. Two of the eight patients complained about nausea and vomiting and one of them abandoned therapy because of sustained gastrointestinal discomfort after 6 months. One patient suffered from intolerable nausea and vomiting and discontinued treatment within 2 weeks.

CONCLUSION

GLP-1 analogues can cause substantial and sustained weight loss in obese patients with hypothalamic disease. This offers a new approach for medical treatment of moderate to severe hypothalamic obesity and associated metabolic alterations.

Long-term outcome in patients with acromegaly: analysis of 1344 patients from the German Acromegaly Register

BACKGROUND

Acromegaly is a rare disease with significant morbidity and increased mortality. Epidemiological data about therapeutic outcome under 'real life' conditions are scarce.

OBJECTIVE

To describe biochemical long-term outcome of acromegaly patients in Germany.

DESIGN AND METHODS

Retrospective data analysis from 1344 patients followed in 42 centers of the German Acromegaly Register. Patients' data were collected 8.6 (range 0-52.6) years after diagnosis. Controlled disease was defined by an IGF1 within the center-specific reference range.

RESULTS

Nine hundred and seventeen patients showed a normalized IGF1 (157 (range 25-443) ng/ml). In patients with a diagnosis dated back >2 years (n=1013), IGF1 was normalized in 76.9%. Of the patients, 19.5% had an elevated IGF1 and a random GH ≥1 ng/ml, 89% of the patients had at least one surgical intervention, 22% underwent radiotherapy, and 43% received medical treatment. After surgery 38.8% of the patients were controlled without any further therapy. The control rates were higher in surgical centers with a higher caseload (P=0.034). Of the patients with adjunctive radiotherapy 34.8% had a normal IGF1 8.86 (0-44.9) years post irradiation, 65.2% of the medically treated patients were controlled, and 47.2% of the patients with an elevated IGF1 received no medical therapy.

CONCLUSION

The majority of acromegaly patients were controlled according to their IGF1 status. Long-term outcome could be improved by exploiting medical treatment options especially in patients who are not controlled by surgery and/or radiotherapy.

Adrenarche and puberty in children with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency

There have been only a few studies on adrenarche in girls with classic congenital adrenal hyperplasia (CAH) showing that dehydroepiandrosterone sulfate (DHEAS) levels did not rise at the physiological age of adrenarche.

OBJECTIVE

Longitudinal analysis of serum DHEAS levels and Tanner stages in CAH children.

DESIGN

We studied 98 CAH patients (52 females), aged between 1 month and 18.0 years. All patients had genetically proven classic CAH and received steroid substitution therapy.

RESULTS

Serum DHEAS levels did not differ between CAH children and healthy children from the age of 1 year until 5-6 years. Beginning at the age of 7-8 years, there was a continuous but blunted increase in DHEAS levels in CAH boys and girls compared to healthy children. There was no correlation of DHEAS levels with the genotype, glucocorticoid dosage, auxological data, or quality of metabolic control. Pubarche (PH2) as well as gonadarche (G2) and thelarche (B2) occurred significantly earlier in CAH boys and girls than in the reference group, but timing of menarche was normal.

CONCLUSIONS

Pubarche and adrenarche are dissociated in classic CAH: earlier pubarche, gonadarche and thelarche, respectively, in both sexes contrast with the absence of typical adrenarche.

Craniopharyngioma in adults

Craniopharyngiomas are slow growing benign tumors of the sellar and parasellar region with an overall incidence rate of approximately 1.3 per million. During adulthood there is a peak incidence between 40 and 44 years. There are two histopathological types, the adamantinomatous and the papillary type. The later type occurs almost exclusively in adult patients. The presenting symptoms develop over years and display a wide spectrum comprising visual, endocrine, hypothalamic, neurological, and neuropsychological manifestations. Currently, the main treatment option consists in surgical excision followed by radiation therapy in case of residual tumor. Whether gross total or partial resection should be preferred has to be balanced on an individual basis considering the extent of the tumor (e.g., hypothalamic invasion). Although the overall long-term survival is good it is often associated with substantial morbidity. Preexisting disorders are often permanent or even exacerbated by treatment. Endocrine disturbances need careful replacement and metabolic sequelae should be effectively treated. Regular follow-up by a multidisciplinary team is a prerequisite for optimal outcome of these patients.

(23)Na magnetic resonance imaging of tissue sodium

Hypertension is linked to disturbed total-body sodium (Na(+)) regulation; however, measuring Na(+) disposition in the body is difficult. We implemented (23)Na magnetic resonance spectroscopy ((23)Na-MR) and imaging technique ((23)Na-MRI) at 9.4T for animals and 3T for humans to quantify Na(+) content in skeletal muscle and skin. We compared (23)Na-MRI data with actual tissue Na(+) content measured by chemical analysis in animal and human tissue. We then quantified tissue Na(+) content in normal humans and in patients with primary aldosteronism. We found a 29% increase in muscle Na(+) content in patients with aldosteronism compared with normal women and men. This tissue Na(+) was mobilized after successful treatment without accompanying weight loss. We suggest that, after further refinements, this tool could facilitate understanding the relationships between Na(+) accumulation and hypertension. Furthermore, with additional technical advances, a future clinical use may be possible.