Distinct clinical phenotypes in a family with a novel truncating MEN1 frameshift mutation.

BACKGROUND: MEN1 mutations can inactivate or disrupt menin function and are leading to multiple endocrine neoplasia type 1, a rare heritable tumor syndrome. CASE PRESENTATION: We report on a MEN1 family with a novel heterozygous germline mutation, c.674delG; p.Gly225Aspfs*56 in exon 4 of the MEN1 gene. Diagnosis and clinical phenotyping of MEN1 was established by laboratory tests, ultrasound, biopsy, MRI imaging and endosonography. The clinical course of the disease was followed in the index patient and her family members for eight years. The mutation was associated with distinct clinical phenotypes in the index patient and three family members harboring p.Gly225Aspfs*56. Family members affected showed primary hyperparathyroidism but variable patterns of associated endocrine tumors, adrenal cortical adenomas, prolactinoma, multifocal pancreatic neuroendocrine tumors, insulinoma and nonsecretory neuroendocrine tumors of the pancreas. The mutation c.674delG; p.Gly225Aspfs*56 leads to a frameshift from codon 225 with early truncation of the menin protein. In silico analysis predicts loss of multiple protein-menin interactions in p.Gly225Aspfs*56, potentially rendering menin insufficient to control cell division and replication. However, no aggressive neuroendocrine tumors were observed in the follow-up of this family. CONCLUSIONS: We report a novel heterozygous MEN1 frameshift mutation, potentially causing (at least partial) inactivation of menin tumor suppression potential but lacking a genotype-phenotype correlation. Our study highlights the importance of personalized care with appropriate testing and counseling in MEN1 families.

Inactivating calcium-sensing receptor mutations in patients with primary hyperparathyroidism.

OBJECTIVE: Primary hyperparathyroidism (HPT) is characterised by autonomous secretion of PTH from enlarged parathyroid glands leading, in most patients, to asymptomatic hypercalcaemia. Familial hypocalciuric hypercalcaemia (FHH) is an autosomal dominant disorder caused by inactivating mutations in the calcium-sensing receptor (CaSR) gene; it is characterised by lifelong and usually asymptomatic hypercalcaemia. Establishing the correct diagnosis is important because surgery can be curative in HPT, but ineffective in FHH. There is overlap in the diagnostic criteria for the two disorders and some patients carrying inactivating mutations in the CaSR gene, which is suggestive of FHH, also have HPT with hyperplastic parathyroid glands or adenomas. DESIGN AND PATIENTS CaSR gene mutations were analysed and clinical and biochemical parameters evaluated in 139 consecutive outpatients presenting with hypercalcaemia and suspected of having HPT. RESULTS: Six different mutations of the CaSR gene were found in eight patients. In four patients, classical FHH was suspected based on clinical and biochemical results and was confirmed by the CaSR mutations. In the other four patients, HPT was diagnosed based on the biochemical profile or symptoms; in these four patients, the parathyroids were operated on and single adenomas were histologically confirmed. In all four patients, serum calcium decreased postoperatively; and in three patients, serum calcium normalised postoperatively. The CaSR mutations in these patients were R25X, E250K and Q926R. CONCLUSION: The coexistence of HPT and FHH in four of 139 patients suggests a pathogenetic role of CaSR mutations in HPT. Despite also having a CaSR mutation, these patients benefited from parathyroid surgery.

Activating mutations in the calcium-sensing receptor: genetic and clinical spectrum in 25 patients with autosomal dominant hypocalcaemia - a German survey.

OBJECTIVE: Autosomal dominant hypocalcaemia or hypoparathyroidism is caused by activating mutations of the calcium-sensing receptor (CaSR). Treatment with calcium and vitamin D often worsens hypercalciuria and nephrocalcinosis, and renal impairment can result. Our aim was to describe the phenotypic variance of this rare disorder in a large series and to evaluate the outcome after long-term treatment. DESIGN: Nationwide retrospective collaborative study. PATIENTS: We describe 25 patients (14 men and 11 women), 20 belonging to 11 families and five single cases. MEASUREMENTS: Activating CaSR mutations and clinical and biochemical findings were evaluated. RESULTS: Nine different missense mutations of the CaSR, including one novel variant (M734T), were found. Twelve patients (50%) were symptomatic, 9 (36%) had basal ganglia calcifications and 3 (12%) had nephrocalcinosis. Serum calcium was decreased (1·87 ± 0·13 mm), and PTH was decreased (n = 19) or inappropriately low (n = 4). The occurrence of hypocalcaemic symptoms at diagnosis was related to the degree of hypocalcaemia. The occurrence of features like calcification of basal ganglia or kidney calcification did not correlate with the severity of hypocalcaemia or the age at diagnosis. The most common treatment was calcitriol (median dosage 0·6 µg/day), and the mean duration of therapy was 7·1 years (max. 26 years). Hypercalcaemic episodes rarely occurred, and the rate of kidney calcifications was remarkably low (12%). CONCLUSION: This series increases the limited knowledge of mutations and phenotypes of this rare disorder. Mutation analysis of the CaSR gene facilitates patient and family management. Low dosages of calcitriol resulted in less frequent renal calcifications.

Bone mineral density and bone turnover in Romanian children and young adults with classical 21-hydroxylase deficiency are influenced by glucocorticoid replacement therapy.

OBJECTIVE: It remains controversial if glucocorticoid replacement therapy impairs bone mineral density (BMD) in young patients with 21-hydroxylase deficiency. We aimed to analyze the impact of treatment variables, phenotype and genotype on BMD and bone metabolism in these patients. DESIGN: Cross-sectional study. MEASUREMENTS: Twenty-eight Caucasian patients with classical 21-hydroxylase deficiency (5-39 years). Clinical parameters, hormonal status, osteocalcin (OC), C-terminal telopeptide of type I collagen (CTX), genotype and lumbar BMD (Z-scores) were assessed. Cumulative and mean hydrocortisone equivalent doses were calculated for the entire treatment period. RESULTS: Patients with severely reduced BMD Z-scores (< or = -2.5 SD) had significantly higher mean/cumulative glucocorticoid doses compared to patients with moderately reduced (P = 0.003/P = 0.026) and normal Z-scores (> -1 SD) (P = 0.005/P = 0.011). Mean hydrocortisone equivalent doses > 20 mg/m(2)/day led to significantly lower lumbar BMD Z-scores (-2.16 +/- 1.4 SD) vs. doses

Typical characteristics of children with congenital adrenal hyperplasia due to 11ß-hydroxylase deficiency: a single-centre experience and review of the literature.

Background 11ß-hydroxylase deficiency (11ßOHD) is a rare disease representing the second most common cause of congenital adrenal hyperplasia (CAH) (5-8%) with an incidence of about 1:100,000. In contrast to 21-hydroxylase deficiency (21OHD), 11ßOHD is not included in neonatal screening programmes. The objective of this study was to demonstrate the typical features of male patients with 11ßOHD. Methods Clinical, biochemical and radiological data of patients with 11ßOHD were analysed in this retrospective single-centre analysis. Results Six male patients of four unrelated families with 11ßOHD were identified (0.1-13.5 years of chronological age [CA] at diagnosis). The predominant symptoms were arterial hypertension, tall stature and precocious pseudopuberty. Bone ages (BAs) were remarkably advanced at diagnosis in four index patients (median difference BA-CA: 5.5 years, range 1.5-9.2 years). Homozygous mutations were identified in exon 7 (c.1179_1180dupGA [p.Asn394Argfs*37]) and exon 8 (c.1398+2T>C) of the CYP11B1 gene leading both to a complete loss of function. The latter mutation has not yet been described in databases. 11ßOHD was identified by the measurement of 11-deoxycortisol in a newborn screening card of one patient retrospectively. Testicular adrenal rest tumours (TARTs) were detected in three patients at 3.7 years, 11 years and 14.4 years. Conclusion The diagnosis of CAH due to 11ßOHD is delayed and should be suspected in children with arterial hypertension, tall stature and precocious pseudopuberty. Patients may develop TARTs as early as infancy. 11ßOHD should be included in newborn screening programmes, at least in newborns of index families, to allow early diagnosis and the start of treatment to reduce morbidity.

Carboxyl-terminal mutations in 3beta-hydroxysteroid dehydrogenase type II cause severe salt-wasting congenital adrenal hyperplasia.

INTRODUCTION: 3beta-Hydroxysteroid dehydrogenase (3beta-HSD) deficiency is a rare cause of congenital adrenal hyperplasia caused by inactivating mutations in the HSD3B2 gene. Most mutations are located within domains regarded crucial for enzyme function. The function of the C terminus of the 3beta-HSD protein is not known. OBJECTIVE: We studied the functional consequences of three novel C-terminal mutations in the 3beta-HSD protein (p.P341L, p.R335X and p.W355X), detected in unrelated 46,XY neonates with classical 3beta-HSD type II deficiency showing different degrees of under-virilization. METHODS AND RESULTS: In vitro expression of the two truncated mutant proteins yielded absent conversion of pregnenolone and dehydroepiandrosterone (DHEA), whereas the missense mutation p.P341L showed a residual DHEA conversion of 6% of wild-type activity. Additional analysis of p.P341L, including three-dimensional protein modeling, revealed that the mutant's inactivity predominantly originates from a putative structural alteration of the 3beta-HSD protein and is further aggravated by increased protein degradation. The stop mutations cause truncated proteins missing the final G-helix that abolishes enzymatic activity irrespective of an augmented protein degradation. Genital appearance did not correlate with the mutants' residual in vitro activity. CONCLUSIONS: Three novel C-terminal mutants of the HSD3B2 gene are responsible for classical 3beta-HSD deficiency. The C terminus is essential for the enzymatic activity. However, more studies are needed to clarify the exact function of this part of the protein. Our results indicate that the genital phenotype in 3beta-HSD deficiency cannot be predicted from in vitro 3beta-HSD function alone.

Novel inactivating mutations of the calcium-sensing receptor: the calcimimetic NPS R-568 improves signal transduction of mutant receptors.

CONTEXT AND OBJECTIVE: Inactivating mutations in the calcium-sensing receptor (CaSR) gene cause neonatal severe hyperparathyroidism and familial hypocalciuric hypercalcemia (FHH). The aims of the present study were the functional characterization of novel mutations of the CaSR found in FHH patients, the comparison of in vitro receptor function with clinical parameters, and the effect of the allosteric calcimimetic NPS R-568 on the signaling of mutant receptors. METHODS: Wild-type and mutant CaSRs (W530G, C568Y, W718X, M734R, L849P, Q926R, and D1005N) were expressed in human embryonic kidney 293 cells. Receptor signaling was studied by measuring intracellular free calcium in response to different concentrations of extracellular calcium ([Ca(2+)](o)). RESULTS: Four CaSR mutations (C568Y, W718X, M734R, and L849P) demonstrated a complete lack of a [Ca(2+)](o)-induced cytosolic Ca(2+) response up to 30 mm [Ca(2+)](o), whereas the CaSR mutants W530G, Q926R, and D1005N retained some sensitivity to [Ca(2+)](o). There was no significant relation between the in vitro calcium sensitivity, serum calcium, and intact PTH levels in the patients. Patients with C-terminal CaSR mutations had a calcium to creatine ratio above the established diagnostic threshold of 0.01 for FHH. The calcimimetic NPS R-568 enhanced the responsiveness to [Ca(2+)](o) in CaSR mutants of the extracellular domain (W530G and C568Y) as well as the intracellular C-terminal domain (Q926R and D1005N). CONCLUSION: Therefore, calcimimetics might offer medical treatment for symptomatic FHH patients, and more important, for patients with neonatal severe hyperparathyroidism that harbor calcimimetic-sensitive CaSR mutants.

A homozygous L299P mutation in the CYP11B1 gene leads to complete virilization in 46,XX individuals with 11-beta-hydroxylase deficiency.

BACKGROUND/AIM: 11-beta-hydroxylase deficiency (11betaOHD) is caused by CYP11B1 gene defects and leads to congenital adrenal hyperplasia associated with hypertension. Recently, a novel L299P mutation has been described in a compound heterozygous male individual. We observed two 46,XX siblings with a homozygous L299P mutation and investigated the functional properties of this CYP11B1 variant. PATIENTS: The index patient from a consanguineous Turkish family showed complete external virilization and was diagnosed incidentally at the age of 19 months during hospital admission for severe combined bacterial (urosepsis) and viral (CMV and EBV) infection. The younger sibling was diagnosed at the age of 5 months. Their genital phenotype was identical and both demonstrated borderline elevated blood pressure. RESULTS: Biochemical findings revealed 11betaOHD. A homozygous L299P mutation of the CYP11B1 gene was detected. In vitro expression studies performed in HCT116 cells showed a markedly decreased CYP11B1 activity in the L299P mutant (1.6 +/- 0.8%) for the conversion of 11-deoxycortisol to cortisol. CONCLUSIONS: Our study provides clear data on the functional properties and clinical phenotype in 46,XX individuals homozygous for this point mutation. Adrenal insufficiency might have contributed to the severe infectious disease that was present in the index patient at diagnosis.

Clinical Features and Response to Treatment of Prolactinomas in Children and Adolescents: A Retrospective Single-Centre Analysis and Review of the Literature.

BACKGROUND: Paediatric prolactinomas are rare. The aim of this study was to investigate the clinical features and outcome of paediatric patients with prolactinomas. METHODS: In this single-centre retrospective analysis, clinical, biochemical, and radiological features of all paediatric patients with pituitary adenomas diagnosed between 2000 and 2016 were evaluated. RESULTS: Among 21 patients with pituitary adenomas, 12 patients with prolactinomas (median age 14.2 years, range 11-16.6 years, 8 females, 4 males) were identified (7 macro- and 5 microprolactinomas). The most common clinical symptoms were headaches (67%) and pubertal delay (67%). All patients with macroprolactinomas with prolactin concentrations >10,000 mU/L had at least 1 pituitary hormone deficiency. Cabergoline as first-line treatment (n = 11, median follow-up of 37 months, range 12-89 months) induced normoprolactinemia (n = 8), reduced the mean tumour volume by 80%, and ameliorated headaches (p = 0.016) and pubertal delay (p = 0.031), whereas intermittent moderate side effects occurred in 55%. CONCLUSION: Adolescents with headaches and pubertal delay should be investigated for prolactinomas. Treatment with cabergoline is well tolerated and effective in reducing clinical symptoms and prolactin concentrations was well as inducing tumour shrinkage. Further clinical prospective studies are needed to standardize paediatric treatment modalities.

Change in the spectrum of RET mutations diagnosed between 1994 and 2006.

Medullary thyroid carcinoma (MTC) is a rare calcitonin producing tumor. About 70-75% of patients with MTC have sporadic disease while the others suffer from hereditary MTC. Hereditary MTC is divided into three clinical subtypes: multiple endocrine neoplasia (MEN) type 2A is characterized by MTC, pheochromocytoma and primary hyperparathyroidism. MEN 2B is characterized by aggressive MTC, pheochromocytoma, marfanoid habitus and the presence of distinctive mucosal neuromas on the tongue, lips and subconjunctival areas as well as ganglioneuromatosis of the gastrointestinal tract. The third clinical subtype of inherited MTC, familial MTC, is defined as the presence of MTC in families without evidence of adrenal or parathyroid gland involvement. Hereditary MTC is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. The first RET germline mutations were identified in 1993 in patients with MEN 2A and FMTC. Initially a codon 634 (exon 11) mutation was found in approximately 85% of patients with MEN 2A, and germline mutations in FMTC kindreds were more equally distributed throughout the RET proto-onocogene. In about 5% of families in these earlier series, mutations did not reside in exons 10 and 11. We now report a change in the spectrum of mutations detected in the RET proto-oncogene in patients with hereditary MTC from the 'classical' mutation at codon 634 in exon 11 (level 2) to more cases with mutations in the exons 13-15 (level 1) and less aggressive disease. In our series 38.9% of mutations were level 1 mutations, 54.4% level 2, and 5.6% level 3 mutations.

Heterozygous inactivating CaSR mutations causing neonatal hyperparathyroidism: function, inheritance and phenotype.

BACKGROUND: Homozygous inactivating mutations of the calcium-sensing receptor (CaSR) lead to neonatal severe hyperparathyroidism (NSHPT), whereas heterozygous inactivating mutations result in familial hypocalciuric hypercalcemia (FHH). It is unknown why in some cases heterozygous CaSR mutations cause neonatal hyperparathyroidism (NHPT) clinically similar to NSHPT but with only moderately elevated serum calcium. METHODS: A literature survey was conducted to identify patients with heterozygous CaSR mutations and NHPT. The common NHPT CaSR mutants R185Q and R227L were compared with 15 mutants causing only FHH in the heterozygous state. We studied in vitro calcium signaling including the functional consequences of co-expression of mutant and wild-type (wt) CaSR, patients' phenotype, age of disease manifestation and mode of inheritance. RESULTS: All inactivating CaSR mutants impaired calcium signaling of wt-CaSR regardless of the patients' clinical phenotype. The absolute intracellular calcium signaling response to physiologic extracellular calcium concentrations in vitro showed a high correlation with patients' serum calcium concentrations in vivo, which is similar in NHPT and FHH patients with the same genotype. Pedigrees of FHH families revealed that paternal inheritance per se does not necessarily lead to NHPT but may only cause FHH. CONCLUSIONS: There is a significant correlation between in vitro functional impairment of the CaSR at physiologic calcium concentrations and the severity of alterations in calcium homeostasis in patients. Whether a particular genotype leads to NHPT or FHH appears to depend on additional predisposing genetic or environmental factors. An individual therapeutic approach appears to be warranted for NHPT patients.

21-Hydroxylase and 11beta-hydroxylase mutations in Romanian patients with classic congenital adrenal hyperplasia.

CONTEXT: Congenital adrenal hyperplasia (CAH) comprises autosomal recessive disorders mainly due to defects in the 21-hydroxylase (CYP21) gene. OBJECTIVE: The study aimed to perform molecular characterization in 43 Romanian patients with classical CAH forms diagnosed at the Center for Genetic Diseases of the Pediatric Clinic/University Cluj (38 with 21-hydroxylase deficiency, five with 11beta-hydroxylase deficiency), to determine the frequency of mutations in the CYP21A2 gene and attempt a genotype-phenotype correlation in patients with 21-hydroxylase deficiency. DESIGN: Molecular analysis was performed by direct sequencing of PCR amplified products of the CYP21A2 and CYP11B1 genes. RESULTS: The most frequent mutation in Romanian patients with 21-hydroxylase deficiency was I2G (43.9%), followed by deletions and large conversions (16.7%), I172N and the triple mutation (P30L+I2G+del8bp), accounting for 12.1% each, P30L (7.6%) and R356W (1.5%). Genotypes were categorized in three mutation groups (0, A, and B), according to their predicted functional consequences, and compared with clinical phenotype. Positive predictive values were 100, 75, and 100% for groups 0, A, and B, respectively. Overall genotype-phenotype correlation was 87.88%. In the five patients with 11beta-hydroxylase deficiency, the following homozygous mutations were identified: T318R in two related patients; R448H in two unrelated patients; and P94L, a new, yet-undescribed mutation. CONCLUSION: The present study is the first countrywide report of mutational analysis in a Romanian patient population with 21-hydroxylase deficiency. Molecular diagnosis was performed in a small number of CAH patients proved not to suffer from 21-hydroxylase deficiency but from 11beta-hydroxylase deficiency, and a new mutation was identified.

Machine learning approaches for phenotype-genotype mapping: predicting heterozygous mutations in the CYP21B gene from steroid profiles.

OBJECTIVE: Non-linear relations between multiple biochemical parameters are the basis for the diagnosis of many diseases. Traditional linear analytical methods are not reliable predictors. Novel nonlinear techniques are increasingly used to improve the diagnostic accuracy of automated data interpretation. This has been exemplified in particular for the classification and diagnostic prediction of cancers based on expression profiling data. Our objective was to predict the genotype from complex biochemical data by comparing the performance of experienced clinicians to traditional linear analysis, and to novel non-linear analytical methods. DESIGN AND METHODS: As a model, we used a well-defined set of interconnected data consisting of unstimulated serum levels of steroid intermediates assessed in 54 subjects heterozygous for a mutation of the 21-hydroxylase gene (CYP21B) and in 43 healthy controls. RESULTS: The genetic alteration was predicted from the pattern of steroid levels with an accuracy of 39% by clinicians and of 64% by linear analysis. In contrast, non-linear analysis, such as self-organizing artificial neural networks, support vector machines, and nearest neighbour classifiers, allowed for higher accuracy up to 83%. CONCLUSIONS: The successful application of these non-linear adaptive methods to capture specific biochemical problems may have generalized implications for biochemical testing in many areas. Nonlinear analytical techniques such as neural networks, support vector machines, and nearest neighbour classifiers may serve as an important adjunct to the decision process of a human investigator not 'trained' in a specific complex clinical or laboratory setting and may aid them to classify the problem more directly.

Pregnancies in patients with congenital adrenal hyperplasia with complete or almost complete impairment of 21-hydroxylase activity.

OBJECTIVE: To show that, with appropriate therapy, women with classic congenital adrenal hyperplasia (CAH) can become pregnant. DESIGN: Observational clinical study. SETTING: University hospital. PATIENT(S): Adult young women with CAH: three with the salt-wasting form and four patients with simple virilizing CAH due to severe homozygous or compound heterozygous mutations of the CYP21B gene (deletions, I172N in exon 4 and nt656A/C-->G in intron 2) who wished to become pregnant. INTERVENTION(S): After confirmation in the first patient of the beneficial effect of additional treatment with fludrocortisone in lowering 17alpha-hydroxyprogesterone (17-OHP) levels, five other patients were treated with hydrocortisone as three daily doses at 8-hour intervals and fludrocortisone 0.1-0.2 mg daily divided into two to three doses. One patient received glucocorticoid alone. MAIN OUTCOME MEASURE(S): Treatment was controlled on the basis of morning salivary 17-OHP estimates and plasma renin concentrations. RESULT(S): Nine pregnancies occurred in six women. The course of the pregnancies (except one spontaneous abortion) was normal without any other modification of therapy. Only the women treated with hydrocortisone alone did not become pregnant. CONCLUSION(S): When treated with a combination of glucocorticoids and mineralocorticoids, sexually active patients with the classic phenotype of CAH can become pregnant.

Mutational analysis and genotype-phenotype correlation in patients with classic 21-hydroxylase deficiency from transylvania (north-west Romania).

The regional incidence of 21-hydroxylase deficiency, its mutational spectrum and the correlation of genotype and phenotype has been studied by European, American and Latin-American groups. However, little information is known about the molecular background of the disease in patients from Central-Eastern Europe. The present study aimed to genotype a group of patients from Transylvania, the north-western part of Romania, in order to gain some insight into the molecular pattern and the genotype-phenotype correlation of congenital adrenal hyperplasia (CAH) in this region. We genotyped 17 patients with classic 21-hydroxylase deficiency and, whenever available, their parents in order to verify mutational segregation. The patients came from 13 unrelated families. DNA was prepared from peripheral blood leucocytes and four gene fragments were amplified by PCR. The 21-hydroxylase gene (CYP21B) was completely sequenced and analyzed for point mutations or deletions. Percentage distribution of mutations was as follows: 12G--34.6%, deletions and large conversions (del)--19.2%, P30L--15.4%, 1172N--15.4%, P30L+I2G+del8bp (triple mutation)--11.5%, and R356W--3.8%. Mutational percentage distribution compared to other Latin populations is higher for I2G and I172N and lower for deletions, while the P30L mutation was found at a higher rate than in any other analyzed population. Some differences may arise from the low patient number and from ethnic particularities. The incidence of compound heterozygotes in our group was 76.5%. The genotype seemed to correlate fairly well to phenotype, with a general concordance rate of 82.35%. Clear divergence was found in two patients with the simple virilizing form, exhibiting a homozygous status for I2G and del, respectively. This study offers the first information about the molecular pathology of CAH in Romania and should help to improve management and clinical outcome for patients with CAH in Transylvania. Hopefully, it might also be the first step towards exact and accurate prenatal diagnosis in our country.

Amino alcohol- (NPS-2143) and quinazolinone-derived calcilytics (ATF936 and AXT914) differentially mitigate excessive signalling of calcium-sensing receptor mutants causing Bartter syndrome Type 5 and autosomal dominant hypocalcemia.

INTRODUCTION: Activating calcium sensing receptor (CaSR) mutations cause autosomal dominant hypocalcemia (ADH) characterized by low serum calcium, inappropriately low PTH and relative hypercalciuria. Four activating CaSR mutations cause additional renal wasting of sodium, chloride and other salts, a condition called Bartter syndrome (BS) type 5. Until today there is no specific medical treatment for BS type 5 and ADH. We investigated the effects of different allosteric CaSR antagonists (calcilytics) on activating CaSR mutants. METHODS: All 4 known mutations causing BS type 5 and five ADH mutations were expressed in HEK 293T cells and receptor signalling was studied by measurement of intracellular free calcium in response to extracellular calcium ([Ca2+]o). To investigate the effect of calcilytics, cells were stimulated with 3 mM [Ca2+]o in the presence or absence of NPS-2143, ATF936 or AXT914. RESULTS: All BS type 5 and ADH mutants showed enhanced signalling activity to [Ca2+]o with left shifted dose response curves. In contrast to the amino alcohol NPS-2143, which was only partially effective, the quinazolinone calcilytics ATF936 and AXT914 significantly mitigated excessive cytosolic calcium signalling of all BS type 5 and ADH mutants studied. When these mutants were co-expressed with wild-type CaSR to approximate heterozygosity in patients, ATF936 and AXT914 were also effective on all mutants. CONCLUSION: The calcilytics ATF936 and AXT914 are capable of attenuating enhanced cytosolic calcium signalling activity of CaSR mutations causing BS type 5 and ADH. Quinazolinone calcilytics might therefore offer a novel treatment option for patients with activating CaSR mutations.

Prevalence and clinical spectrum of nonsecretory medullary thyroid carcinoma in a series of 839 patients with sporadic medullary thyroid carcinoma.

BACKGROUND: Medullary thyroid carcinoma (MTC) is characterized by the synthesis and secretion of calcitonin (Ct). MTC without Ct secretion has been reported on rare occasions. The aim of this study was to analyze the prevalence and clinical spectrum of nonsecretory MTC in two tertiary centers that cared for 839 patients with sporadic MTC. METHODS: Clinical, biochemical, histological, and immunohistological findings, and somatic RET mutations were analyzed, and long-term follow-up was documented. RESULTS: Seven patients with nonsecretory MTC were identified among 839 patients with sporadic MTC; thus, the prevalence rate of nonsecretory MTC was 0.83%. In these seven patients, Ct and carcinoembryonic antigen (CEA) levels were normal when MTC was initially diagnosed in the patients, despite advanced tumor stage. Ct and CEA levels remained undetectable in four patients; recurrence was indicated in one patient after 10 years of follow-up by routine anatomic imaging and increased CEA levels, and Ct levels became slightly elevated during follow-up, despite massive tumor load, in the remaining two patients. The diagnosis of MTC was confirmed by positive immunohistochemistry for Ct, CEA, and chromogranin A. A high Ki67 proliferation index (PI) (three patients) and a high proportion of RET 918-mutated cells (four patients), as well as poorly differentiated histology, were associated with aggressive biological behavior of the MTC. The prognosis for nonsecretory MTC varied between long-term survival (12.5 years) and rapid progression leading to death within 1.75 years after diagnosis. CONCLUSIONS: The prevalence of nonsecretory MTC was low (0.83% of patients with MTC). Diagnosis was often made at a clinically advanced tumor stage. The histological and immunohistological characteristics and the clinical course and prognosis of nonsecretory MTC are markedly heterogeneous. A high Ki-67 PI and a large proportion of cells with RET 918 mutations are associated with a poor prognosis.

Diagnosis of glucocorticoid-remediable aldosteronism in hypertensive children.

OBJECTIVE: Glucocorticoid-remediable aldosteronism (GRA) is caused by the presence of a chimeric gene originating from an unequal cross-over between the CYP11B1 and CYP11B2 genes. Aldosterone suppression by dexamethasone and high 18-hydroxycortisol (18-OHF) levels have been used to differentiate GRA from the other forms of primary aldosteronism. METHODS: A dexamethasone suppression test including serum 18-OHF determination and the measurement of urinary excretion of aldosterone, its metabolites and 18-OHF were performed in 3 children of a family with primary aldosteronism. Polymerase chain reactions were performed to identify the chimeric gene. RESULTS: The chimeric gene was identified in 2 children, their mother and grandmother. The affected children had an aldosterone-to-plasma renin activity ratio >30, elevated serum 18-OHF concentration and increased urinary excretion of aldosterone, its metabolites, and 18-OHF. Post-dexamethasone concentrations of serum aldosterone and 18-OHF concentrations were suppressed. CONCLUSION: Although very rare, the possible diagnosis of GRA should be considered in all children or young adults with low-renin hypertension. Since genetic testing is more specific than biochemical testing, a definitive diagnosis can only be obtained by identification of the CYP11B1/CYP11B2 chimeric gene.

CDC73-related hereditary hyperparathyroidism: five new mutations and the clinical spectrum.

OBJECTIVE: Hyperparathyroidism-jaw tumour (HPT-JT) syndrome is a rare autosomal dominant cause of benign and malignant parathyroid tumours, ossifying jaw tumours, various cystic and neoplastic renal abnormalities and benign and malignant uterine tumours. Disease-causing mutations have been localised in the tumour suppressor gene CDC73. There is limited information available on the mutations, and resulting phenotypes and long-term follow-up data are especially scarce. DESIGN: We analysed the clinical data from 16 patients (including three families) carrying mutations in the CDC73 gene. We describe five new mutations/gene variants, the corresponding phenotypes of these carriers and the long-term follow-up. METHODS: The 16 patients were evaluated at an endocrine outpatient clinic and at a surgical department. DNA samples were obtained for sequence analysis of the CDC73 gene. RESULTS: Clinical features of HPT-JT syndrome were detected in 13 of the 15 carriers with germline CDC73 mutations. The major features were benign (n=7; 47%) or cancerous (n=3; 20%) HPT-JT was present in eight cases (53%). Most patients had severe hypercalcaemia, and median serum calcium levels were 3.36 mmol/l. A patient with non-secretory parathyroid carcinoma was included. HPT was diagnosed at a median age of 28.5 years. Mutational analysis of the CDC73 gene identified eight sequence changes, three of them have been reported previously, whereas five are novel: c.1346delG, c.88_94delTTCTCCT, the non-coding variants, c.307+5G>T and c.424-5T>C and c.*12C>A of unknown significance. CONCLUSIONS: This study significantly increases the information available on the mutations and phenotypes of HPT-JT syndrome.

Novel activating mutations of the calcium-sensing receptor: the calcilytic NPS-2143 mitigates excessive signal transduction of mutant receptors.

CONTEXT AND OBJECTIVE: Activating mutations in the calcium-sensing receptor (CaSR) gene cause autosomal dominant hypocalcemia (ADH). The aims of the present study were the functional characterization of novel mutations of the CaSR found in patients, the comparison of in vitro receptor function with clinical parameters, and the effect of the allosteric calcilytic NPS-2143 on the signaling of mutant receptors as a potential new treatment for ADH patients. METHODS: Wild-type and mutant CaSR (T151R, P221L, E767Q, G830S, and A844T) were expressed in human embryonic kidney cells (HEK 293T). Receptor signaling was studied by measuring intracellular free calcium in response to different concentrations of extracellular calcium ([Ca(2+)](o)) in the presence or absence of NPS-2143. RESULTS: All ADH patients had lowered serum calcium ranging from 1.7 to 2.0 mm and inadequate intact PTH and urinary calcium excretion. In vitro testing of CaSR mutations from these patients revealed exaggerated [Ca(2+)](o)-induced cytosolic Ca(2+) responses with EC(50) values for [Ca(2+)](o) ranging from 1.56 to 3.15 mM, which was lower than for the wild-type receptor (4.27 mM). The calcilytic NPS-2143 diminished the responsiveness to [Ca(2+)](o) in the CaSR mutants T151R, E767Q, G830S, and A844T. The mutant P221L, however, was only responsive when coexpressed with the wild-type CaSR. CONCLUSION: Calcilytics might offer medical treatment for patients with autosomal dominant hypocalcemia caused by calcilytic-sensitive CaSR mutants.