Multicentre study evaluating the surgical learning curve for posterior retroperitoneoscopic adrenalectomy.

BACKGROUND: Posterior retroperitoneoscopic adrenalectomy has gained international popularity in the past decade. Despite major advantages, including shorter duration of operation, minimal blood loss and decreased postoperative pain, many surgeons still prefer laparoscopic transperitoneal adrenalectomy. It is likely that the unfamiliar anatomical environment, smaller working space and long learning curve impede implementation. The present study assessed the number of procedures required to fulfil the surgical learning curve for posterior retroperitoneoscopic adrenalectomy. METHODS: The first consecutive posterior retroperitoneoscopic adrenalectomies performed by four surgical teams from university centres in three different countries were analysed. The primary outcome measure was duration of operation. Secondary outcomes were conversion to an open or laparoscopic transperitoneal approach, complications and recovery time. The learning curve cumulative sum (LC-CUSUM) was used to assess the learning curves for each surgical team. RESULTS: A total of 181 surgical procedures performed by four surgical teams were analysed. The median age of the patients was 57 (range 15-84) years and 61·3 per cent were female. Median tumour size was 25 (range 4-85) mm. There were no significant differences in patient characteristics and tumour size between the teams. The median duration of operation was 89 (range 29-265) min. There were 35 perioperative and postoperative complications among the 181 patients (18·8 per cent); 17 of 27 postoperative complications were grade 1. A total of nine conversions to open procedures (5·0 per cent) were observed. The LC-CUSUM analysis showed that competency was achieved after a range of 24-42 procedures. CONCLUSION: In specialized endocrine surgical centres between 24 and 42 procedures are required to fulfil the entire surgical learning curve for the posterior retroperitoneoscopic adrenalectomy.

Clinical signs of fibrosis in small intestinal neuroendocrine tumours.

BACKGROUND: In patients with small intestinal neuroendocrine tumours (SI-NETs), serotonin and other cytokines released from tumour cells may induce fibrosis, leading to carcinoid heart disease and abdominal fibrotic reactions. The aim of this study was to assess the prevalence, clinical complications and management of this reaction in the abdomen. METHODS: This was a retrospective cohort study of patients with SI-NETs diagnosed between 1985 and 2015. Clinical data, outcomes, radiological findings, and surgical and radiological interventions were reviewed. RESULTS: A total of 824 patients were diagnosed with SI-NETs in the study interval. Clinically significant abdominal signs and symptoms of fibrosis occurred in 36 patients. Of these, 20 had critically symptomatic central mesenteric fibrosis causing obstruction of mesenteric vessels, and 16 had retroperitoneal fibrosis causing obstructive uropathy with hydronephrosis. Extensive fibrosis causing mesenteric vessel obstruction and/or obstructive uropathy was more often associated with symptomatic and advanced disease encompassing lymph node metastases in the mesenteric root, para-aortic lymph node metastases, as well as liver metastases and peritoneal carcinomatosis. Palliative intervention in terms of superior mesenteric vein stenting or resection of central mesenteric metastases and/or percutaneous nephrostomy and J stent treatment was beneficial in the majority of the patients. CONCLUSION: Extensive abdominal fibrosis associated with clinically significant symptoms of intestinal ischaemia and/or obstructive uropathy was linked to advanced disease in patients with SI-NETs. Prompt recognition and minimally invasive intervention was effective in disease palliation.

Genetics of adrenocortical tumours.

The recently available genomic sequencing techniques have led to breakthroughs in understanding of the underlying genetic mechanisms in adrenocortical tumours. Disease-causing mutations have been described for aldosterone-producing adenomas, cortisol-producing adenomas and adrenocortical carcinomas. Further, knowledge gained from transcriptome analyses and methylation arrays has provided new insights into the development of these tumours. Elucidation of the genomic landscape of adrenocortical tumours and improved techniques may in the future be useful for early diagnosis through the detection of mutated DNA in the circulation. Moreover, compounds that bind specifically to altered proteins may be used as screening targets or therapeutic agents. Regulation of cortisol release by interaction with an altered subunit in adenylate cyclase may be more complex, but may provide a new option for regulating steroid release. Information about derangements in adrenocortical carcinoma is already helpful for determining patient prognosis. With further knowledge, we may be able to identify novel biomarkers that effectively and noninvasively help in differentiating between benign and malignant disease. It is clear that the next few years will provide much novel information that hopefully will aid in the treatment of patients with adrenocortical tumours.

Exome Sequencing and CNV Analysis on Chromosome 18 in Small Intestinal Neuroendocrine Tumors: Ruling Out a Suspect?

The genetic background in small intestinal neuroendocrine tumors is poorly understood, but several studies have revealed numerical imbalances. Loss of one copy of chromosome 18 is the most frequent genetic aberration in this tumor type, which indirectly suggests that a driver mutation may be present in the remaining allele. The aim of this study was to evaluate the mutation status on chromosome 18 in small intestinal neuroendocrine tumors. DNAs from 7 small intestinal neuroendocrine tumors were subjected to whole exome capture, followed by next generation sequencing and high resolution SNP array followed by copy number variation analysis. Exome capture sequencing generated an average coverage of 50.6-138.2. Only 19 genes were covered less than 8X. No tumor-specific somatic mutation was identified. Genomic profiling revealed loss of chromosome 18 in 5 out of 7 small intestinal neuroendocrine tumors and a number of other aberrancies. Loss of chromosome 18 is the most frequent genetic aberration in small intestinal neuroendocrine tumors, but no evidence for eventual mutations in the remaining allele. This suggests involvement of other mechanisms than point mutations in small intestinal neuroendocrine tumors tumorigenesis.

Outcome after resection and radiofrequency ablation of liver metastases from small intestinal neuroendocrine tumours.

BACKGROUND: In patients with small intestinal neuroendocrine tumour (SI-NET), liver resection or radiofrequency ablation (RFA) of liver metastases is performed for palliation of carcinoid syndrome, and in an effort to improve survival. Data are generally reported from case series, and no randomized trials have studied these treatments. The aim was to compare outcome after liver resection and/or RFA with that of non-surgical treatment in patients with liver metastases from SI-NET. METHODS: The study included patients with liver metastases from SI-NET who underwent liver RFA/resection or were treated non-surgically. A propensity score match was performed to reduce bias between groups, using baseline variables such as the Charlson co-morbidity index, age, symptoms, carcinoid heart disease, extent of metastases and proliferation index. RESULTS: Some 103 patients who had RFA and/or liver resection were compared with 273 controls. Propensity score matching resulted in two matched groups, each of 72 patients, with no significant differences in baseline variables. The matched resection/RFA and control groups showed no difference in overall survival (both 74 per cent at 5 years; P = 0·869) or disease-specific survival (74 versus 78 per cent respectively at 5 years; P = 1·000). However, urinary 5-hydroxyindoleacetic acid levels were lower (median 77 versus 120 µmol per 24 h; P = 0·005) and the proportion of patients with progressive disease within the liver was smaller (2 of 18 versus 8 of 18; P < 0·001) in the resection/RFA group after 5 years. CONCLUSION: These data do not support the use of liver resection and/or RFA in an effort to prolong survival in patients with liver metastases from SI-NET.

Vitamin D receptor genotypes in primary hyperparathyroidism.

Vitamin D and parathyroid hormone (PTH) constitute the main regulators of systemic calcium homeostasis. As well as its calcaemic effects, active vitamin D3(1,25(OH)2D3) has a direct regulatory role on parathyroid cells. Active vitamin D3 acts via its receptor (VDR), and binding of the ligand-receptor complex to specific promoter regions of the PTH gene inhibits transcription. Active vitamin D3 constitutes a principal regulator of parathyroid cell growth, and polymorphism in the VDR gene has recently been related to bone mineral density and suggested as predisposing to osteoporosis. Impaired effects of active vitamin D3 may contribute to the relatively enhanced secretion and cell proliferation seen in hyperparathyroidism (HPT). Indeed, VDR dysfunction, of essentially unknown character, has been demonstrated in the pathological parathyroid tissue of primary HPT as well as HPT secondary to uraemia. Consistent with the essential role of active vitamin D3 in parathyroid regulation, the VDR gene polymorphism was studied in 90 postmenopausal women with primary hyperparathyroidism. The VDR genotype bb was found in 60.0% of HPT patients and in 33.3% of the postmenopausal female controls (P < 0.001). As the b allele has been linked to decreased transcriptional activity or messenger RNA stability, reduced VDR expression may impede regulatory actions of vitamin D and may contribute to parathyroid tumorigenesis in these patients.

Primary small intestinal neuroendocrine tumors are highly prevalent and often multiple before metastatic disease develops.

BACKGROUND: Small intestinal neuroendocrine tumors are the most common of small bowel malignancies with a clinical incidence of about 1 per 100,000 persons per year. There has been a threefold increase in the incidence of small intestinal neuroendocrine tumor during later decades, but there are no studies that clarify whether this is due to a true higher incidence or if the rise is a mere product of, for instance, improved diagnostic modalities. The aim of this study was to investigate the incidence of clinical as well as subclinical small intestinal neuroendocrine tumors found at autopsy as well as describing the frequency of concomitant malignancies in patients with small intestinal neuroendocrine tumor. MATERIALS AND METHODS: An autopsy registry from the Malmö county population from 1970 to 1982 with an 87% autopsy rate was used. The clinical autopsy reports for patients coded for the existence of "carcinoid tumor" were scrutinized for the presence of small intestinal neuroendocrine tumor, metastatic disease, and concomitant malignancies. Details of patients with clinically diagnosed small intestinal neuroendocrine tumor during this time period were gathered from the Swedish Cancer Registry. RESULTS: The mean annual incidence of small intestinal neuroendocrine tumor during this period was 5.33 per 100,000 individuals, and the mean annual prevalence was 581 per 100,000. The cause of death in the majority of cases was not due to small intestinal neuroendocrine tumor. In total, 48% of the people with small intestinal neuroendocrine tumor had at least one other malignancy, most commonly colorectal cancer. CONCLUSION: Most small intestinal neuroendocrine tumors are subclinical, and persons living with them will often die due to other causes. There was a high rate of multiple primary tumors (40%), suggesting that multiple tumors seem to arise before the advent of metastatic disease. Moreover, a comparably high rate of associated colorectal carcinoma was found.

Long-term outcome after resection and thermal hepatic ablation of pancreatic neuroendocrine tumour liver metastases.

BACKGROUND: Pancreatic neuroendocrine tumours (Pan-NETs) are rare tumours that often present with or develop liver metastases. The aim of this retrospective study was to evaluate liver surgery and thermal hepatic ablation (THA) of Pan-NET liver metastases and to compare the outcomes with those of a control group. METHOD: Patients with Pan-NET treated in Uppsala University Hospital and Sahlgrenska University Hospital from 1995-2018 were included. Patient records were scrutinized for baseline parameters, survival, treatment and complications. RESULTS: Some 108 patients met the criteria for inclusion; 57 patients underwent treatment with liver surgery or THA and 51 constitute the control group. Median follow-up was 3.93 years. Five-year survival in the liver surgery/THA group was 70.6 (95 per cent c.i. 0.57 to 0.84) per cent versus 42.4 (95 per cent c.i. 40.7 to 59.1) per cent in the control group (P = 0.016) and median survival was 9.1 (95 per cent c.i. 6.5 to 11.7) versus 4.3 (95 per cent c.i. 3.4-5.2) years. In a multivariable analysis, surgery or THA was associated with a decreased death-years rate (hazard ratio 0.403 (95 per cent c.i. 0.208 to 0.782, P = 0.007). CONCLUSION: Liver surgery and/or THA was associated with longer overall survival in Pan-NET with acceptable mortality and morbidity rates. These treatments should thus be considered in Pan-NET patients with reasonable tumour burden in an intent to alleviate symptoms and to improve survival.

Randomized clinical trial comparing open with video-assisted minimally invasive parathyroid surgery for primary hyperparathyroidism.

BACKGROUND: : Previous studies of video-assisted techniques for parathyroidectomy in patients with primary hyperparathyroidism have found similar or better results compared with bilateral neck exploration. The aim of the present study was to compare open minimally invasive parathyroidectomy with the video-assisted technique for primary hyperparathyroidism in a multicentre randomized trial. METHODS: : Some 143 patients were randomized to open (n = 75) or video-assisted (n = 68) parathyroidectomy after positive sestamibi scintigraphy. There were no differences in preoperative data. The open operation was performed through a 15-mm incision. The video-assisted techniques used were minimally invasive video-assisted parathyroidectomy (MIVAP) or video-assisted parathyroidectomy using the lateral approach (VAPLA). Data were collected prospectively including postoperative pain scoring. RESULTS: : The procedure was significantly quicker for the open compared to the video assisted operations: mean(s.d.) 60(35) versus 84(47) min (P = 0.001). Both groups of patients had similar conversion rates and the same outcome, with comparable incision lengths, low scores for postoperative neck discomfort, high cosmetic satisfaction and low complication rates. CONCLUSION: : Open minimally invasive parathyroidectomy for primary hyperparathyroidism was quicker than either video-assisted technique. REGISTRATION NUMBER: NCT00877981 (http://www.clinicaltrials.gov)

11C-metomidate positron emission tomography after dexamethasone suppression for detection of small adrenocortical adenomas in primary aldosteronism.

PURPOSE: To evaluate whether dexamethasone suppression treatment can improve (11) C-metomidate positron emission tomography (MTO-PET) detection of small adrenocortical adenomas in primary aldosteronism (PA). MATERIALS AND METHODS: Eleven patients with proven PA and two patients with non-hyperfunctioning adrenocortical incidentalomas and small adrenocortical tumours observed on CT underwent MTO-PET before and 3 days after administration of oral dexamethasone suppression treatment. Small "hot-spot" regions of interest comprising 4 pixels (SUVhs) and 1 pixel (SUVmax) were placed in the tumour area with the highest radioactivity concentration and their respective standardised uptake values (SUV) were recorded. RESULTS: All tumours were detected and categorised as adrenocortical by MTO-PET. SUVhs as well as SUVmax were higher in PA compared to nonfunctional adenomas. Normal adrenal cortex was suppressed after dexamethasone (p < 0.05), but tumour SUV was not significantly decreased after suppression in either PA or nonfunctional tumours (p > 0.05). However, these changes caused no significant increase in the tumour-to-normal adrenal ratio (p > 0.05). CONCLUSION: MTO-PET is a highly sensitive method for detecting and categorising even small adrenocortical tumours in PA. In this series, dexamethasone-suppressed MTO-PET was unable to increase the tumour-to-normal adrenal ratio to further facilitate detection of small adenomas in PA as an alternative to adrenal venous sampling.

Long-term effects of surgical correction of adrenal hyperplasia and adenoma causing primary aldosteronism.

PURPOSE: The purpose of this is to study long-time results of surgery for primary aldosteronism. MATERIALS AND METHODS: Thirty patients operated on for primary aldosteronism were followed for an average of 7 years. All but five required potassium substitution. Systolic as well as diastolic hypertension (mean 157/93 mmHg) was present necessitating one to five antihypertensive drugs daily (mean 2.33). Preoperative indications for surgery included presumed adenoma (aldosterone-producing adenoma (APA)) or in one case unilateral dominance of hyperplasia. RESULTS: Histopathology was classified into adenoma (n = 9), dominant nodule (n = 16), and general hyperplasia without dominating nodules (n = 5), demonstrating a higher frequency of hyperplasia than anticipated. Long-term results revealed well-controlled blood pressure (BP; mean 134/80 mmHg). Antihypertensive medication was reduced (average of 1.78 per day), but only 36% of the patients were taken off these drugs completely. S-Aldosterone was normalized. All but one (a recurrence) were normokalemic without potassium substitution at follow-up. The APA group needed less medication (median 0.5 vs. 1.5 and 2 per day) and more patients in this group were totally medication free (50%). Two recurrences occurred in the group with general hyperplasia without dominating nodules. CONCLUSION: Nodular hyperplasia is more common than anticipated. Hypersecretion of aldosterone may be released from a large nodule identified as an adenoma, as well as from a generally hyperplastic gland that has not been identified as such. Nevertheless, surgery for lateralized disease results in good long-term control of BP with less antihypertensive medication. However, patients with dominant nodule or general hyperplasia without dominating nodules need more postoperative treatment than patients with APA. The majority of patients do not achieve normotension without medications, but they do become normokalemic.

Adrenocorticotropin-independent Cushing's syndrome in pregnancy related to overexpression of adrenal luteinizing hormone/human chorionic gonadotropin receptors.

Cushing's syndrome during pregnancy is rare, and rather than being of pituitary origin most patients exhibit ACTH-independent adrenal hypercortisolism. In some cases the syndrome has spontaneously resolved post partum, suggesting the presence of a pregnancy-associated stimulatory factor(s). We describe a case with aberrant adrenal LH/hCG receptors in a large adrenal tumor as a possible explanation for cortisol hypersecretion and tumor growth in Cushing s syndrome during pregnancy. A 27-yr-old woman presented with hypertension and diabetes mellitus in early pregnancy. Investigations revealed hypercortisolemia, suppressed ACTH-levels, and a 6.4- cm right adrenal tumor. The tumor was successfully removed by laparoscopy at 26th week of pregnancy. Hypercortisolism and hypertension resolved post-operatively. The tumor displayed higher LH/hCG receptor mRNA and protein positivity than adjacent normal adrenal tissue as examined by in situ hybridization and immunocytochemistry. High physiological levels of hCG, in conjunction with aberrant adrenal LH/hCG receptor overexpression, may have contributed to the development of Cushing's syndrome in pregnancy.

Increased ratio of mRNA expression of the genes CYP17 and CYP11B1 indicates autonomous cortisol production in adrenocortical tumors.

OBJECTIVE: Due to increased use of imaging techniques, adrenal incidentalomas are frequently detected. The majority are non-hyperfunctioning adrenocortical tumors. We have previously shown that expression of the gene CYP17, coding for the enzyme in the cortisol pathway, correlates with cortisol release from adrenocortical tumors in vitro. The aim of this study was to compare clinical data with mRNA expression of CYP17 and CYP11B1 in adrenocortical tumors from patients with and without Cushing's syndrome and to identify adrenal tumors that may cause subclinical Cushing's syndrome. DESIGN: A retrospective study of 34 patients undergoing adrenalectomy due to an adrenal tumor. METHODS: Clinical data were collected. In the adrenal gland the mRNA expression of the genes CYP17 and CYP11B1 was studied with in situ hybridisation technique. RESULTS: The median ratio of CYP17/CYP11B1 expression in tumors from patients with Cushing's syndrome was significantly higher than the median ratio in the non-hyperfunctioning tumors. Tumors from 2 patients with subclinical Cushing's syndrome had ratios within the upper range for non-hyperfunctioning tumors. CONCLUSIONS: The ratio between the expression of the genes CYP17 and CYP11B1 in tumors from patients with Cushing's syndrome is significantly higher than in the non-hyperfunctioning tumors. This indicates that 17alpha-hydroxylase is a major determinant of cortisol overproduction. The patients with subclinical Cushing's syndrome in this study are too few to draw any firm conclusions although the results suggest that subclinical Cushing's syndrome may be identified post-operatively with this method.

Prognostic factors for death after surgery for small intestinal neuroendocrine tumours.

BACKGROUND: Neuroendocrine tumours of the small intestine (SI-NETs) are rare gastrointestinal neoplasms with an annual incidence of about one per 100 000. Patients with apparently similar tumours have variable outcomes. The aim of this study was to identify postoperative prognostic factors identifiable after initial surgery. METHODS: This was a nested case-control study of patients with SI-NETs who were treated between 1961 and 2001. Data were retrieved from the Swedish Cancer Registry. Patients who died from the SI-NET and corresponding controls (who outlived cases by at least 1 month), matched by age at diagnosis and calendar period, were included. Sex, postoperative symptoms, postoperative 5-hydroxyindoleacetic acid (5-HIAA) values, European Neuroendocrine Tumor Society (ENETS) stage, insufficiency of the tricuspid valve, radical secondary surgery and secondary malignancy were studied as potential prognostic factors. RESULTS: In total, 1122 patients were included (561 cases, 561 controls). Postoperative factors of prognostic importance included hormone-related symptoms, stage IV disease, raised levels of 5-HIAA, insufficiency of the tricuspid valve, secondary surgery not being macroscopically radical and a second malignancy. CONCLUSION: Stage and symptomatic disease are important prognostic factors in SI-NET.

25-hydroxyvitamin D3 1alpha-hydroxylase and vitamin D receptor expression in papillary thyroid carcinoma.

Vitamin D receptor (VDR) and 25-hydroxyvitamin D3 1-alpha-hydroxylase expression have recently been shown to be upregulated in several tumors and thought to represent an important endogenous response to tumor progression. Little is known about the expression of these proteins in thyroid carcinoma, although previous reports have documented evidence of the biological effect of vitamin D in thyroid cells. Using paraffin-embedded and frozen sections of papillary thyroid carcinoma, we utilized real-time quantitative RT-PCR and immunohistochemistry to characterize the expression of VDR and 1-alpha-hydroxylase in thyroid follicular cells, with special emphasis on papillary thyroid carcinoma (PTC). VDR and 1-alpha-hydroxylase expression were increased in PTC compared with normal thyroid tissue and especially high in areas of lymphocyte infiltration. Expression of VDR and 1-alpha-hydroxylase in PTC may be compatible with an overall favorable prognosis for this tumor type and may constitute important prerequisites for using vitamin D and/or vitamin D analogs in the treatment of PTC.

Mutation of the multiple endocrine neoplasia type 1 gene in nonfamilial, malignant tumors of the endocrine pancreas.

Endocrine pancreatic tumors are rare neoplasms that occur sporadically or as part of a multiple endocrine neoplasia type 1 (MEN1) syndrome. Germ-line mutations of the MEN1 gene, located at 11q13, have been demonstrated in MEN1 kindreds, and loss of heterozygosity (LOH) on 11q13 together with somatic MEN1 mutations have been detected in 20% of nonfamilial parathyroid tumors. Here, we examine 11 non-MEN1 malignant tumors of the endocrine pancreas, 9 nonfunctioning tumors, and 2 glucagonomas. LOH of at least one informative locus on 11q13 was found in 70% of the tumors. Three tumors displayed somatic mutations of the MEN1 gene together with LOH on 11q13, whereas the corresponding germ-line DNA was normal. These findings support the hypothesis that MEN1 gene mutations contribute to the tumorigenesis of nonfamilial, malignant endocrine pancreatic tumors.

Vitamin D receptor polymorphisms correlate to parathyroid cell function in primary hyperparathyroidism.

Calcitriol acts via its receptor (VDR) and inhibits PTH secretion and parathyroid cell proliferation. Increased prevalence of the polymorphic VDR alleles b, a, and T has been demonstrated in sporadic primary hyperparathyroidism. Sixty-two patients with primary hyperparathyroidism due to parathyroid adenoma (mean age, 69.5 +/- 1.4 yr) were genotyped for these VDR polymorphisms. Dispersed cells of the adenomas were exposed to increasing concentrations of extracellular Ca2+ and analyzed for PTH release and cytoplasmic Ca2+ concentrations. Ca2+-mediated PTH inhibition exhibited higher ED50 and less suppression in the cells of patients who were homozygous for the b, a, and T alleles (P < 0.05-0.10). When analyzing haplotypes, the patients with baT demonstrated a ED50 of 1.81 +/- 0.15 vs. 1.29 +/- 0.10 for BAt (P < 0.05). As VDR alleles were unrelated to parathyroid intracellular Ca2+, influences of polymorphic VDR alleles on PTH secretion seem to involve mechanisms other than the Ca2+-sensing protein of the parathyroid cell surface.

Familial hypercalcemia and hypercalciuria caused by a novel mutation in the cytoplasmic tail of the calcium receptor.

Familial hyperparathyroidism (HPT), characterized by hypercalcemia and hypercalciuria, and familial benign hypocalciuric hypercalcemia (FHH) are the most common causes of hereditary hypercalcemia. The calcium-sensing receptor (CaR) regulates PTH secretion and renal calcium excretion. Heterozygous inactivating mutations of the gene cause FHH, whereas CaR gene mutations have not been demonstrated in HPT. In a kindred with 20 affected individuals, the hypercalcemic disorder segregated with inappropriately higher serum PTH and magnesium levels and urinary calcium levels than in unaffected members. Subtotal parathyroidectomy revealed parathyroid gland hyperplasia/adenoma and corrected the biochemical signs of the disorder in seven of nine individuals. Linkage analysis mapped the condition to markers flanking the CaR gene on chromosome 3q. Sequence analysis revealed a mutation changing phenylalanine to leucine at codon 881 of the CaR gene, representing the first identified point mutation located within the cytoplasmic tail of the CaR. A construct of the mutant receptor (F881L) was expressed in human embryonic kidney cells (HEK 293), and demonstrated a right-shifted dose-response relationship between the extracellular and intracellular calcium concentrations. The hypercalcemic disorder of the present family is caused by an inactivating point mutation in the cytoplasmic tail of the CaR and displays clinical characteristics atypical of FHH and primary HPT.