Neonatal Severe Primary Hyperparathyroidism Research Articles

Generation of CRISPR/Cas9 modified human iPSC line with correction of heterozygous mutation in exon 6 of the CaSR gene.

The calcium-sensing receptor (CaSR) gene encodes a cell membrane G protein-coupled receptor (GPCR) which has a key role in maintaining the extracellular Ca2+ homeostasis. We aimed at correcting the compound heterozygous mutation in the 6th [c.1656delA, p.I554SfsX73] and 7th [c.2217T > A, p.C739X] exons of the CASR gene which the original patient-derived iPSC line had. The mutation is associated with neonatal severe primary hyperparathyroidism of the patient. We generated and characterized a CRISP/Cas9-edited hiPSC line with the restored sequence in the sixth exon of the CASR gene, bearing only heterozygous mutation in the 7th exon. The results showed that the new genetically modified cell line has karyotype without abnormalities, typical hiPSCs morphology, characteristic expression of pluripotency markers, and ability to develop into three germ layers, and differentiates in chondrogenic, adipogenic, osteogenic directions. This new cell line will complement the existing pool of CaSR-mutated cell lines, a valuable resource for in-depth understanding of neonatal severe primary hyperparathyroidism. This will allow further exploration of the application of pharmacological drugs in the context of personalized medicine to correct Ca-homeostasis disorders.

Familial states of primary hyperparathyroidism: an update.

Familial primary hyperparathyroidism (PHPT) includes syndromic and non-syndromic disorders. The former are characterized by the occurrence of PHPT in association with extra-parathyroid manifestations and includes multiple endocrine neoplasia (MEN) types 1, 2, and 4 syndromes, and hyperparathyroidism-jaw tumor (HPT-JT). The latter consists of familial hypocalciuric hypercalcemia (FHH) types 1, 2 and 3, neonatal severe primary hyperparathyroidism (NSHPT), and familial isolated primary hyperparathyroidism (FIHP). The familial forms of PHPT show different levels of PHPT penetrance, developing earlier and with multiglandular involvement compared to sporadic counterpart. All these diseases exhibit Mendelian inheritance patterns, and for most of them, the genes responsible have been identified. DNA testing for predisposing mutations is helpful in index cases or in individuals with a high suspicion of the disease. Early recognition of hereditary disorders of PHPT is of great importance for the best clinical and surgical approach. Genetic testing is useful in routine clinical practice because it will also involve appropriate screening for extra-parathyroidal manifestations related to the syndrome as well as the identification of asymptomatic carriers of the mutation. The aim of the review is to discuss the current knowledge on the clinical and genetic profile of these disorders along with the importance of genetic testing in clinical practice.

Neonatal Severe Primary Hyperparathyroidism—Presentation, Management, and Follow-up of Seven Cases

Neonatal Severe Primary Hyperparathyroidism—Presentation, Management, and Follow-up of Seven Cases

Suspecting Neonatal Severe Primary Hyperparathyroidism in Late Onset Neonatal Sepsis

Background: Neonatal severe primary hyperparathyroidism (NSPHPT) is disorder characterized by severe hypercalcemia and severe hyperparathyroidism resulting from a loss of function of the calcium-sensing receptor (CaSR), encoded by a gene located on the long arm of chromosome 3 (3q-13.3-21). It can be fatal if timely management is not initiated. Clinical Description: A 10-day-old exclusively breastfed girl presented with poor feeding, constipation, and lethargy for 2–3 days before admission. She was born of third-degree consanguinity to a primiparous woman with normal gestation. Born at term, with a birth weight of 3.1 kg, she was discharged uneventfully on day 3 of life. At admission, she was hemodynamically stable and normothermic but exhibited tachypnea, dehydrated with 15% weight loss as compared to birth weight, lethargy, and hypotonia. Salient investigations showed euglycemia, no dyselectrolytemia, and negative sepsis screen, but severe hypercalcemia and hyperparathyroidism. A final diagnosis of NSPHPT was made. Clinical exome sequencing showed homozygous CaSR gene frameshift mutation on chromosome 3. Management: Hypercalcemia was managed initially by standard protocol, including furosemide, hyperhydration, bisphosphonates, and cinacalcet. Subsequently, parathyroidectomy was performed at 2 months of age. Postoperatively, the infant is 5 months old and thriving well. Conclusion: NSPHPT should be considered in the presence of features of clinical sepsis, failure to timely regain birth weight, and a profile suggesting atypical calcium homeostasis.

Generation of an induced pluripotent stem cell line HPCASRi002-A from a patient with neonatal severe primary hyperparathyroidism caused by a compound heterozygous mutation in the CASR gene

Neonatal severe primary hyperparathyroidism (NSHPT) is a rare autosomal recessive disorder of calcium homeostasis that manifests shortly after birth with hypercalcemia and bone disease. NSHPT, in most cases, is attributed to mutations in the calcium-sensing receptor (CASR) gene. We reprogrammed dermal fibroblasts derived from a patient with NSHPT carrying a compound heterozygous mutation in the CASR gene into induced pluripotent stem cells (iPSCs). The established iPSCs expressed pluripotency markers, maintained normal karyotype and differentiated into all three germ layers. This line is a valuable resource for modeling of hyperparathyroidism related to CASR mutations.

Severe primary hyperparathyroidism in a 3-day-old neonate

Neonatal severe primary hyperparathyroidism (NSHPT) is a rare and life-threatening autosomal recessive genetic disorder caused by a wide range of inactivating mutations in Calcium sensing receptors. We introduced a three-day-old neonate with poor feeding, failure to thrive, and lethargy. The laboratory results showed uncontrolled hypercalcemia with hyperparathyroidism; therefore, the patient was referred to a pediatric surgeon for parathyroidectomy. We showed that neonates with NSHPT could be treated with total parathyroidectomy with autotransplant without transplant-induced hypercalcemia.

Neonatal Severe Primary Hyperparathyroidism: A Series of Four Cases and their Long-term Management in India.

Context:Neonatal severe primary hyperparathyroidism (NSPHPT) is an extremely rare autosomal recessive disorder, requiring a high index of suspicion. Infants affected with this disorder present with severe life-threatening hypercalcemia early in life, requiring adequate preoperative medical management followed by surgery.Aims:We report four newborns with NSPHPT who were managed over 10 years.Subjects and Methods:Demography, clinical presentation, treatment, and follow-up data were retrospectively studied with descriptive analysis to highlight the utility of long-term medical management, surgery, and genetic testing reported in the literature.Statistical Analysis Used:Descriptive Analysis.Results:We had three males and one female infant with a mean age of diagnosis at 28.7 days, calcium 29.2+/-2.8 mg/dL, and parathormone (PTH) 1963+/-270.4 pg/mL. All four infants presented with failure to thrive, hypotonia, and respiratory distress. All infants were treated medically followed by total parathyroidectomy plus transcervical thymectomy, with an additional hemithyroidectomy in one of them. Imaging was negative in all four cases. Three babies became hypocalcemic while the fourth infant had a drop in PTH and is on the tab. cinacalcet 30 mg/day. CaSR mutation was positive in three infants.Conclusions:Diagnosing NSPHPT needs expert clinical acumen. It requires emergency medical management to control calcium levels. The crisis may present later, necessitating parathyroidectomy in these cases once the child is fit for surgery. Surgery offers a cure for this unusual lethal hypercalcemia while the role of cinacalcet needs a special mention. Sound knowledge in endocrinology with parathyroid embryology and morphology is of paramount importance. Our case series might add a few insights into managing this unusual genetic disorder.

Evolution of Our Understanding of the Hyperparathyroid Syndromes: A Historical Perspective.

We review advancing and overlapping stages for our understanding of the expressions of six hyperparathyroid (HPT) syndromes: multiple endocrine neoplasia type 1 (MEN1) or type 4, multiple endocrine neoplasia type 2A (MEN2A), hyperparathyroidism-jaw tumor syndrome, familial hypocalciuric hypercalcemia, neonatal severe primary hyperparathyroidism, and familial isolated hyperparathyroidism. During stage 1 (1903 to 1967), the introduction of robust measurement of serum calcium was a milestone that uncovered hypercalcemia as the first sign of dysfunction in many HPT subjects, and inheritability was reported in each syndrome. The earliest reports of HPT syndromes were biased toward severe or striking manifestations. During stage 2 (1959 to 1985), the early formulations of a syndrome were improved. Radioimmunoassays (parathyroid hormone [PTH], gastrin, insulin, prolactin, calcitonin) were breakthroughs. They could identify a syndrome carrier, indicate an emerging tumor, characterize a tumor, or monitor a tumor. During stage 3 (1981 to 2006), the assembly of many cases enabled recognition of further details. For example, hormone non-secreting skin lesions were discovered in MEN1 and MEN2A. During stage 4 (1985 to the present), new genomic tools were a revolution for gene identification. Four principal genes ("principal" implies mutated or deleted in 50% or more probands for its syndrome) (MEN1, RET, CASR, CDC73) were identified for five syndromes. During stage 5 (1993 to the present), seven syndromal genes other than a principal gene were identified (CDKN1B, CDKN2B, CDKN2C, CDKN1A, GNA11, AP2S1, GCM2). Identification of AP2S1 and GCM2 became possible because of whole-exome sequencing. During stages 4 and 5, the newly identified genes enabled many studies, including robust assignment of the carriers and non-carriers of a mutation. Furthermore, molecular pathways of RET and the calcium-sensing receptor were elaborated, thereby facilitating developments in pharmacotherapy. Current findings hold the promise that more genes for HPT syndromes will be identified and studied in the near future. © 2018 American Society for Bone and Mineral Research.

Familial and Hereditary Forms of Primary Hyperparathyroidism.

Individuals with a familial predisposition to the development of parathyroid tumors constitute a small minority of all patients with primary hyperparathyroidism (PHPT). These familial syndromes exhibit Mendelian inheritance patterns and the main causative genes in most families have been identified. They include multiple endocrine neoplasia (MEN; types 1, 2A, and 4), hyperparathyroidism-jaw tumor (HPT-JT) syndrome, familial isolated hyperparathyroidism, familial hypocalciuric hypercalcemia (FHH), and neonatal severe PHPT. Each MEN type is associated with the various combinations of specific tumors. MEN1 is characterized by the occurrence of parathyroid, enteropancreatic, and pituitary tumors; MEN2A is characterized by medullary thyroid carcinoma and pheochromocytoma, and MEN4 is characterized by a pathological spectrum similar to that of MEN1 in association with tumors of the adrenal, kidney, and reproductive organs. HPT-JT is characterized by PHPT, ossifying fibromas of maxillary bones, kidney disease, and uterine neoplasias. The prompt diagnosis of these diseases is of great importance for planning appropriate surveillance of the mutant carriers and correct surgical management. The search for mutation is also useful for the identification of the family members who do not carry the mutation and can avoid unnecessary biochemical and instrumental evaluations. Surgery remains the treatment of choice in all familial forms except FHH.

Familial Hyperparathyroidism - Disorders of Growth and Secretion in Hormone-Secretory Tissue.

Six syndromes of familial hyperparathyroidism are compared: 1) Familial hypocalciuric hypercalcemia (FHH) expresses primary hyperparathyroidism (PHPT) beginning at birth with lifelong hypercalcemia. There is nonsuppressed PTH secretion from outwardly normal parathyroid glands. It reflects germline heterozygous mutation in CASR, GNA11, or AP2S1. 2) Neonatal severe primary hyperparathyroidism is severest of the six syndromes. It requires urgent total parathyroidectomy in infancy. It usually reflects biallelic inactivation of the CASR. 3) Multiple endocrine neoplasia type 1 (MEN1) is most frequently expressed as PHPT with asymmetric enlargement of 3-4 parathyroids. Benign or malignant tumors may occur among 30 other tissues. It is predisposed by germline inactivation of MEN1 or rarely by inactivation of a cyclin dependent kinase inhibitor, and then termed MEN4. 4) Multiple endocrine neoplasia type 2A from RET activating mutation rarely presents as familial hyperparathyroidism, because medullary thyroid cancer and pheochromocytoma are more prominent. 5) Hyperparathyroidism-jaw tumor syndrome (HPT-JT) has frequent PHPT and benign jaw tumors. Twenty percent develop parathyroid cancer. It is predisposed by inactivating mutation in CDC73. 6) Familial isolated hyperparathyroidism causes multiple parathyroid tumors. It can be an incomplete expression of FHH, MEN1, HPT-JT or even of relatives without a shared driver mutation. However, in 20% of families it reflects GCM2 activating mutation. Five of the PHPT syndromes reflect overgrowth of parathyroid tissue; in contrast, familial hypocalciuric hypercalcemia reflects dysregulation of PTH secretion with little or no parathyroid overgrowth. These differences underlie major differences in clinical expression.

Hypercalcemic Disorders in Children.

ABSTRACTHypercalcemia is defined as a serum calcium concentration that is greater than two standard deviations above the normal mean, which in children may vary with age and sex, reflecting changes in the normal physiology at each developmental stage. Hypercalcemic disorders in children may present with hypotonia, poor feeding, vomiting, constipation, abdominal pain, lethargy, polyuria, dehydration, failure to thrive, and seizures. In severe cases renal failure, pancreatitis and reduced consciousness may also occur and older children and adolescents may present with psychiatric symptoms. The causes of hypercalcemia in children can be classified as parathyroid hormone (PTH)‐dependent or PTH‐independent, and may be congenital or acquired. PTH‐independent hypercalcemia, ie, hypercalcemia associated with a suppressed PTH, is commoner in children than PTH‐dependent hypercalcemia. Acquired causes of PTH‐independent hypercalcemia in children include hypervitaminosis; granulomatous disorders, and endocrinopathies. Congenital syndromes associated with PTH‐independent hypercalcemia include idiopathic infantile hypercalcemia (IIH), William's syndrome, and inborn errors of metabolism. PTH‐dependent hypercalcemia is usually caused by parathyroid tumors, which may give rise to primary hyperparathyroidism (PHPT) or tertiary hyperparathyroidism, which usually arises in association with chronic renal failure and in the treatment of hypophosphatemic rickets. Acquired causes of PTH‐dependent hypercalcemia in neonates include maternal hypocalcemia and extracorporeal membrane oxygenation. PHPT usually occurs as an isolated nonsyndromic and nonhereditary endocrinopathy, but may also occur as a hereditary hypercalcemic disorder such as familial hypocalciuric hypercalcemia, neonatal severe primary hyperparathyroidism, and familial isolated primary hyperparathyroidism, and less commonly, as part of inherited complex syndromic disorders such as multiple endocrine neoplasia (MEN). Advances in identifying the genetic causes have resulted in increased understanding of the underlying biological pathways and improvements in diagnosis. The management of symptomatic hypercalcemia includes interventions such as fluids, antiresorptive medications, and parathyroid surgery. This article presents a clinical, biochemical, and genetic approach to investigating the causes of pediatric hypercalcemia. © 2017 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

A challenging case of neonatal hyperparathyroidism

Neonatal severe primary hyperparathyroidism (NSPHT) is rare disease in neonates, characterized by hypercalcemia, failure to thrive, skeletal demineralization and often multiple fractures. NSPHT induced hypercalcemia is often refractory to conventional medical therapy and may demand technically challenging surgery. We herein report a case of a neonate with NSPHT, due to novel mutation, who failed medical therapy including calcimimetics and underwent total parathyroidectomy with tracheostomy in our setup.

Hyperplasia in glands with hormone excess.

Five syndromes share predominantly hyperplastic glands with a primary excess of hormones: neonatal severe primary hyperparathyroidism, from homozygous mutated CASR, begins severely in utero; congenital non-autoimmune thyrotoxicosis, from mutated TSHR, varies from severe with fetal onset to mild with adult onset; familial male-limited precocious puberty, from mutated LHR, expresses testosterone oversecretion in young boys; hereditary ovarian hyperstimulation syndrome, from mutated FSHR, expresses symptomatic systemic vascular permeabilities during pregnancy; and familial hyperaldosteronism type IIIA, from mutated KCNJ5, presents in young children with hypertension and hypokalemia. The grouping of these five syndromes highlights predominant hyperplasia as a stable tissue endpoint and as their tissue stage for all of the hormone excess. Comparisons were made among this and two other groups of syndromes, forming a continuum of gland staging: predominant oversecretions express little or no hyperplasia; predominant hyperplasias express little or no neoplasia; and predominant neoplasias express nodules, adenomas, or cancers. Hyperplasias may progress (5 of 5) to neoplastic stages while predominant oversecretions rarely do (1 of 6; frequencies differ P<0.02). Hyperplasias do not show tumor multiplicity (0 of 5) unlike neoplasias that do (13 of 19; P<0.02). Hyperplasias express mutation of a plasma membrane-bound sensor (5 of 5), while neoplasias rarely do (3 of 14; P<0.002). In conclusion, the multiple distinguishing themes within the hyperplasias establish a robust pathophysiology. It has the shared and novel feature of mutant sensors in the plasma membrane, suggesting that these are major contributors to hyperplasia.

The calcium sensing receptor: from calcium sensing to signaling.

The Ca(2+)-sensing receptor (the CaSR), a G-protein-coupled receptor, regulates Ca(2+) homeostasis in the body by monitoring extracellular levels of Ca(2+) ([Ca(2+)]o) and responding to a diverse array of stimuli. Mutations in the Ca(2+)-sensing receptor result in hypercalcemic or hypocalcemic disorders, such as familial hypocalciuric hypercalcemia, neonatal severe primary hyperparathyroidism, and autosomal dominant hypocalcemic hypercalciuria. Compelling evidence suggests that the CaSR plays multiple roles extending well beyond not only regulating the level of extracellular Ca(2+) in the human body, but also controlling a diverse range of biological processes. In this review, we focus on the structural biology of the CaSR, the ligand interaction sites as well as their relevance to the disease associated mutations. This systematic summary will provide a comprehensive exploration of how the CaSR integrates extracellular Ca(2+) into intracellular Ca(2+) signaling.

Identification of 70 calcium-sensing receptor mutations in hyper- and hypo-calcaemic patients: evidence for clustering of extracellular domain mutations at calcium-binding sites

The calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that has an extracellular bilobed venus flytrap domain (VFTD) predicted to contain five calcium (Ca(2+))-binding sites. To elucidate the structure-function relationships of the VFTD, we investigated 294 unrelated probands with familial hypocalciuric hypercalcaemia (FHH), neonatal severe primary hyperparathyroidism (NSHPT) or autosomal dominant hypocalcaemic hypercalciuria (ADHH) for CaSR mutations and performed in vitro functional expression studies and three-dimensional modelling of mutations involving the VFTD. A total of 70 different CaSR mutations were identified: 35 in FHH, 10 in NSHPT and 25 in ADHH patients. Furthermore, a CaSR variant (Glu250Lys) was identified in FHH and ADHH probands and demonstrated to represent a functionally neutral polymorphism. NSHPT was associated with a large proportion of truncating CaSR mutations that occurred in the homozygous or compound heterozygous state. Thirty-four VFTD missense mutations were identified, and 18 mutations were located within 10 Å of one or more of the predicted Ca(2+)-binding sites, particularly at the VFTD cleft, which is the principal site of Ca(2+) binding. Mutations of residues 173 and 221, which are located at the entrance to the VFTD cleft binding site, were associated with both receptor activation (Leu173Phe and Pro221Leu) and inactivation (Leu173Pro and Pro221Gln), thereby highlighting the importance of these residues for entry and binding of Ca(2+) by the CaSR. Thus, these studies of disease-associated CaSR mutations have further elucidated the role of the VFTD cleft region in Ca(2+) binding and the function of the CaSR.

Successful Use of Bisphosphonate and Calcimimetic in Neonatal Severe Primary Hyperparathyroidism

Neonatal primary hyperparathyroidism (NPHT) is associated with an inactivating homozygous mutation of the calcium sensing receptor (CaSR). The CaSR is expressed most abundantly in the parathyroid glands and the kidney and regulates calcium homeostasis through its ability to modulate parathormone secretion and renal calcium reabsorption. NPHT leads to life threatening hypercalcemia, nephrocalcinosis, bone demineralization, and neurologic disabilities. Surgery is the treatment of choice. While waiting for surgery, bisphosphonates offer a good alternative to deal with hypercalcemia. Cinacalcet is a class II calcimimetic that increases CaSR affinity for calcium, leading to parathormone suppression and increased calcium renal excretion. At present, there is little evidence as to whether cinacalcet could improve the function of mutant CaSR in NPHT. We report a case of NPHT, treated successfully with bisphosphonates and cinacalcet after surgery failure. To our knowledge, it is the first time cinacalcet has been used for NPHT.

Calcium-sensing receptor: Role in health and disease

The calcium-sensing receptor (CaSR) is a 1,078 amino acid G protein-coupled receptor (GPCR), which is predominantly expressed in the parathyroids and kidney. The CaSR allows regulation of parathyroid hormone (PTH) secretion and renal tubular calcium re-absorption in response to alterations in extracellular calcium concentrations. Loss-of-function CaSR mutations have been reported in the hypercalcemic disorders of familial benign (hypocalciuric) hypercalcemia (FBH or FHH), neonatal severe primary hyperparathyroidism (NSHPT), and adult primary hyperparathyroidism. However, some individuals with loss-of-function CaSR mutations remain normocalcemic. Gain-of-function CaSR mutations have been shown to result in autosomal-dominant hypocalcemia with hypercalciuria (ADHH) and Bartter's syndrome type V. CaSR auto-antibodies have been found in FHH patients who did not have loss-of-function CaSR mutations and in patients with an acquired form (i.e. autoimmune) of hypoparathyroidism. Thus, abnormalities of the CaSR are associated with 4 hypercalcemic and 3 hypocalcemic disorders.

Needle in a Haystack—Parathyroid Gland in a 10-Day Old Infant: A Case Report and Literature Review

Neonatal severe primary hyperparathyroidism (NSPHT) is a rare autosomal recessive disorder of calcium homeostasis. It presents shortly after birth and is characterized by striking hyperparathyroidism, marked hypercalcemia, and hyperparathyroid bone disease. It is caused by mutations of the calcium-sensing receptor (CASR), the ionized calcium sensor for the parathyroid cells, the parafollicular thyroid C cells, and the kidney epithelium, as well as cells in bone and intestine. Without early intervention, which frequently requires surgical removal of the hyperplastic parathyroids, the patients often succumb to complications of hypercalcemia and respiratory failure. Finding the parathyroid gland in small neonates is not an easy task. Here we report on a patient with neonatal hyperparathyroidism who was treated by total parathyroidectomy and discuss the various ways of helping to find the parathyroid glands during surgery at this young age.

A homozygous inactivating calcium‐sensing receptor mutation, Pro339Thr, is associated with isolated primary hyperparathyroidism: correlation between location of mutations and severity of hypercalcaemia

Inactivating mutations of the calcium-sensing receptor (CaSR), a G-protein-coupled receptor with extracellular (ECD), transmembrane (TMD) and intracellular (ICD) domains, cause familial hypocalciuric hypercalcaemia, neonatal severe primary hyperparathyroidism and occasionally primary hyperparathyroidism in adults. To investigate a patient with typical symptomatic primary hyperparathyroidism for CaSR abnormalities. PATIENT AND DESIGN: A 51-year-old woman with primary hyperparathyroidism was investigated for CaSR abnormalities as her severe hypercalcaemia (3·75 mm) persisted after the removal of two large parathyroid adenomas and she was the daughter of normocalcaemic consanguineous parents. Following informed consent, CASR mutational analysis was undertaken using leucocyte DNA. Wild-type and mutant CaSR constructs were expressed in human embryonic kidney (HEK) 293 cells and assessed by measuring their intracellular calcium responses to changes in extracellular calcium. Clinical data were pooled with previous studies to search for genotype-phenotype correlations. The proband was homozygous for a Pro339Thr CaSR missense mutation, located in the ECD, and her normocalcaemic relatives were heterozygous. The mutant Thr339 CaSR had a rightward shift in its dose-response curve with a significantly higher EC(50) = 3·18 mm ± 0·19 compared to the wild-type EC(50) = 2·16 mm ± 0·1 (P < 0·01), consistent with a loss-of-function mutation. An analysis of CaSR mutations in patients with primary hyperparathyroidism revealed that those of the ECD were associated with a significantly greater hypercalcaemia that was less likely to be corrected after removal of the parathyroid tumours. A CaSR missense mutation causing a loss-of-receptor-function can cause symptomatic primary hyperparathyroidism in adulthood.

Did cinacalcet help in the management of neonatal severe primary hyperparathyroidism secondary to a novel homozygous inactivating mutation of the calcium-sensing receptor?

Did cinacalcet help in the management of neonatal severe primary hyperparathyroidism secondary to a novel homozygous inactivating mutation of the calcium-sensing receptor?