Search

ContextAlthough a monoallelic mutation in the calcium-sensing receptor (CASR) gene causes familial hypocalciuric hypercalcemia (FHH), the functional characterization of the identified CASR mutation linked to the clinical response to calcimimetics therapy is still limited.ObjectiveA 45-year-old male presenting with moderate hypercalcemia, hypocalciuria, and inappropriately high parathyroid hormone (PTH) had a good response to cinacalcet (total serum calcium (Ca2+) from 12.5 to 10.1 mg/dl). We identified the genetic mutation and characterized the functional and pathophysiological mechanisms, and then linked the mutation to calcimimetics treatment in vitro.DesignSanger sequencing of the CASR, GNA11, and AP2S1 genes was performed in his family. The simulation model was used to predict the function of the identified mutant. In vitro studies, including immunoblotting, immunofluorescence, a cycloheximide chase study, Calbryte™ 520 Ca2+ detection, and half-maximal effective concentration (EC50), were examined.ResultsThis proband was found to carry a de novo heterozygous missense I554N in the cysteine-rich domain of CASR, which was pathogenic based on the different software prediction models and ACGME criteria. The simulation model showed that CASR I554N mutation decreased its binding energy with Ca2+. Human CASR I554N mutation attenuated the stability of CASR protein, reduced the expression of p-ERK 1/2, and blunted the intracellular Ca2+ response to gradient extracellular Ca2+ (eCa2+) concentration. The EC50 study also demonstrated the correctable effect of calcimimetics on the function of the CASR I554N mutation.ConclusionThis novel CASR I554N mutation causing FHH attenuates CASR stability, its binding affinity with Ca2+, and the response to eCa2+ corrected by therapeutic calcimimetics.

ContextA germline mutation can be identified in up to 10% of patients with primary hyperparathyroidism (PHPT). In 2017, a high frequency of the GCM2 [(NM_ 004752.4) c.1181A> C; p.Tyr394Ser; rs142287570] variant was reported in PHPT Ashkenazi Jews (AJ).ObjectiveTo evaluate the presence of the GCM2 p.Tyr394Ser variant in Israeli patients addressed for genetic evaluation to characterize their phenotype and clinical management.MethodPatients with PHPT who underwent addressed for genetic screening for suspected familial hypocalciuric hypercalcemia (FHH), a family history of isolated hyperparathyroidism (FIHP), or failed parathyroidectomy with persistent PHPT were recruited. Those with normal initial selected gene sequencing or hyperparathyroid genetic panel completed the GCM2 p.Tyr394Ser variant sequencing. The prevalence of this variant was evaluated using our local genomic database.ResultsA total of 42 single individuals from unrelated kindreds were evaluated. A disease-causing mutation was found in 11 (26.1%) patients: 10 were diagnosed with FHH (eight CASR and two AP2S1 mutations), and one patient had a CKN2B mutation. In 28 of the remaining patients, the GCM2 p.Tyr394Ser variant was positive in three (10.7%), and all were AJ. Within AJ (15/28, 53.5%), the rate of the p.Tyr394Ser variant was 3/15 (20%), and of those, two had a history of familial isolated hyperparathyroidism. Multi-glandular parathyroid adenoma/hyperplasia was also observed in two of these patients. No clinical or laboratory findings could discriminate patients with the GCM2 p.Tyr394Ser variant from those with FHH. Cinacalcet normalized the calcium levels in one patient. The prevalence of the GCM2 p.Tyr394Ser variant in 15,407 tests in our local genomic database was 0.98%.ConclusionIn contrast to previous observations, the GCM2 p.Tyr394Ser variant-associated phenotype may be mild in AJ with FIHP, sometimes mimicking FHH. Because surgery may be curative, surgeons should be aware of the possibility of multiple gland diseases in these patients. The clinical spectrum and clinical utility of screening for this variant warrant further investigation.

IntroductionThe occurrence of prolactinomas in sex hormone treated patients with central hypogonadism is extremely rare.Case presentationWe present a Caucasian male patient who was diagnosed with Kallmann syndrome (KS) at age 15 years. Testosterone treatment was started. At age 26 the patient presented with mild headache. MRI revealed two separate pituitary adenomas along with the absence of the olfactory bulbs. Given the presence of marked hyperprolactinemia (17x upper limit of the reference range) the diagnosis prolactinoma was made and treatment with cabergoline was started which resulted in a complete biochemical response and in marked reduction of both adenomas in size. Hypogonadism persisted and testosterone replacement therapy was continued. Genetic testing of genes associated with pituitary tumors, Kallmann syndrome and idiopathic hypogonadotropic hypogonadism was negative. Mild concomitant hypercalcemia in accordance with familial hypocalciuric hypercalcemia (FHH) prompted mutation analysis of the calcium receptor (CASR) gene which yielded a pathogenic inactivating variant.Discussion/conclusionThe presence of two separate prolactinomas in a patient with KS has not yet been reported in the literature. The effect of sex hormone treatment of KS patients on the possible development of prolactinoma is unknown at present. The occurance of multiple prolactinomas in our patient suggests increased susceptibility. Although CaSR is expressed in GnRH neurons in mouse brain and CaSR deficient mice have a reduced hypothalamic GnRH neuronal population, the relevance of the CASR gene variant in our patient for the KS phenotype is unclear at present.

Familial hypocalciuric hypercalcemia (FHH) is a benign disease associated with heterozygous inactivating mutations in the calcium-sensing receptor (CaSR) gene. This article presents a girl with heterozygous p.Cys575Tyr variation in the CaSR gene. The serum calcium level of a 9.2-year-old girl was 12.4mg/dl in incidental laboratory analysis. On the same occasion, the serum parathyroid hormone (PTH) level was 45 pg/ml, 25(OH) vitamin D level 24.2ng/ml, 1.25 dihydroxy vitamin D level 22pg/ml, and urinary Ca/creatinine ratio A) variation was detected in the patient's CaSR gene, which was reported before, but no clinical manifestations were specified. In children with asymptomatic hypercalcemia, the diagnosis of FHH should be considered if the PTH level is normal or high and the urinary calcium is low. [Med-Science 2022; 11(4.000): 1731-3]

Abstract Background Familial hypocalciuric hypercalcemia (FHH) is a rare autosomal dominant disease, which requires differential diagnosis from relatively common primary hyperparathyroidism (PHPT) in order to avoid unnecessary surgery. Case presentation A 16-year-old female had been followed by the department of psychosomatic medicine at our institution. Throughout the follow-up period, her plasma calcium levels were high, plasma Pi levels were relatively low, and plasma intact PTH was relatively high. She was referred to our department to determine the cause of her hypercalcemia. Her 24 h urinary calcium excretion was as low as 100 mg/day, and calcium creatinine clearance ratio was below 0.01. Moreover, she had a family history of hypercalcemia (proband, her brother, and her father). The genetic testing for her family revealed that she, her brother, and her father were definitively diagnosed with FHH type 1 due to the heterozygous calcium-sensing receptor mutation (NM_00388:4:c.164C > T:p.Pro55Leu). Conclusion We experienced a 16-year-old female with FHH, in whom genetic testing identified the heterozygous calcium-sensing receptor mutation (NM_00388:4:c.164C > T:p.Pro55Leu) as pathogenic, permitting a definitive diagnosis of FHH type 1. The genetic testing for calcium sensing receptor is beneficial to distinguish asymptomatic primary hyperparathyroidism from FHH.

Abstract Background Primary hyperparathyroidism (PHPT) and familial hypocalciuric hypercalcemia (FHH) are the most important differential diagnosis of parathyroid hormone (PTH)-dependent hypercalcemia. The clinical features of FHH and PHPT can overlap in some cases. Therefore, these two diseases must be differentiated to prevent unnecessary parathyroidectomy. Here, we present a case that was not entirely matched with any of the known differential diagnoses of hypercalcemia. Case presentation A 19-year-old girl with no history of any disease presented with persistent hypercalcemia without any specific musculoskeletal complaint. We found persistent hypercalcemia in her routine laboratory data from 3 years ago; while no data was available during the childhood period. Her dietary calcium intake was normal. She did not mention any history of renal stone, bone fracture as well as family history of hypercalcemia. Biochemical features showed normal values of serum creatinine, high normal serum calcium (range, 10.3–11.3 mg/dL; (normal range: 8.8–10.4)), and non-suppressed PTH levels (range, 37.2–58.1 pg/mL; (normal range: 10–65)). Serum 25 OH vitamin D level at the first visit was 16.1 ng/mL that treated by vitamin D supplementation. Since then, all 25 OH vitamin D levels were in the acceptable range. After correction of vitamin D deficiency during the follow-up period the calcium creatinine clearance ratio(s) (CCCR) were calculated in the range of 0.009 to 0.014 (means below 1%). The clinical and laboratory data indicate more FHH rather than PHPT. Genetic studies were negative for the common genes associated with FHH (CASR, GNA11, and AP2S1 genes) and multiple endocrine neoplasia type1 (MEN1). On the other hand, no evidence of autoimmunity was found in her to support an autoimmune FHH-like syndrome. Hence, the case did not match completely to any diagnosis of FHH and PHPT, so we decided to follow her. Conclusion We presented a patient with FHH phenotype whose common genetic tests were negative. Further research is needed to ascertain other causes leading to similar manifestations.

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant inherited disorder due to inactivating mutations in the calcium-sensing receptor (CaSR), less commonly in the G-protein subunit α11 (GNA11) or the adaptor-related protein complex 2, sigma 1 subunit (AP2S1) genes. It is characterized by mild to moderate hypercalcemia, hypocalciuria, and inappropriately normal or high PTH levels. The disorder is usually asymptomatic, and bone or renal involvement is rare. Adequate differential diagnosis between primary hyperparathyroidism and FHH is important to avoid unnecessary surgery. We report the case of a male patient with FHH showing biochemical heterogeneity to highlight the difficulties of differential diagnosis

Background: Loss-of-function variants in the calcium-sensing receptor (CASR) gene are known to be involved in a clinical spectrum ranging from asymptomatic familial hypocalciuric hypercalcemia (FHH) to neonatal severe hyperparathyroidism (NSHPT). Homozygous or compound heterozygous variants are usually responsible for severe neonatal forms, whereas heterozygous variants cause benign forms. One recurrent pathogenic variant, p.Arg185Gln, has been reported in both forms, in a heterozygous state. This variant can be a de novo occurrence or can be inherited from a father with FHH.NSHPT leads to global hypotonia, failure to thrive, typical X-ray anomalies (diffuse demineralization, fractures, metaphyseal irregularities), and acute respiratory distress which can be fatal. Phosphocalcic markers show severe hypercalcemia, abnormal urinary calcium resorption, and hyperparathyroidism as major signs.Classical treatment involves calcium restriction, hyperhydration, and bisphosphonates. Unfortunately, the disease often leads to parathyroidectomy. Recently, calcimimetics have been used with variable efficacy. Efficacy in NSHPT seems to be particularly dependent on CASR genotype. Case presentation: We describe the antenatal presentation of a male with short ribs, initially suspected having skeletal ciliopathy. At birth, he presented with NSHPT linked to the pathogenic heterozygous CASR variant, Arg185Gln, inherited from his father who had FHH. Postnatal therapy with cinacalcet was successful. Discussion: An exhaustive literature review permits a comparison with all reported cases of Arg185Gln and to hypothesize that cinacalcet efficacy depends on CASR genotype. This confirms the importance of pedigree and parental history in antenatal short rib presentation and questions the feasibility of phosphocalcic exploration during pregnancy or prenatal CASR gene sequencing in the presence of specific clinical signs. It could in fact enable early calcimimetic treatment which might be effective in the CASR variant Arg185Gln.

Familial hypocalciuric hypercalcemia (FHH, [OMIM #145980]) is recognized as a benign endocrine condition affecting PTH and calcium levels due to heterozygous inactivating mutations in the calcium sensing receptor (CaSR). The condition is often un- or misdiagnosed but may have a prevalence as high as 74 in 100.000. Here, the neonatal courses of two brothers with paternally inherited FHH (CaSR c.554G>A; p.(Arg185Gln)) are described. The older brother was born preterm at 25 weeks gestation with hypercalcemia and hyperparathyroidism. The younger brother, born full-term, had severe hyperparathyroidism, muscular hypotonia, thrombocytopenia, failure to thrive and multiple metaphyseal fractures. Treatment with cinacalcet was initiated, which resulted in subsequent reduction of PTH levels and prompt clinical improvement. While it is known that homozygous mutations in CaSR may lead to life-threatening forms of neonatal severe hyperparathyroidism (NSHPT), few reports have described a severe clinical course in neonates with FHH due to heterozygous mutations. However, based on the pathophysiological framework, in de novo or paternally transmitted FHH the differing calcium needs of mother and fetus can be expected to induce fetal hyperparathyroidism and may result in severe perinatal complications as described in this report. In summary, FHH is a mostly benign condition, but transient neonatal hyperparathyroidism may occur in affected neonates if the mutation is paternally inherited. If severe, the condition can be treated successfully with cinacalcet. Patients with FHH should be informed about the risk of neonatal disease manifestation in order to monitor pregnancies and neonates.

Primary hyperparathyroidism (PHPT) is sporadic in the majority of cases. Hereditary forms of PHPT are rarer, however, they are of particular interest because they allow a deeper understanding of pathogenesis of parathyroid neoplasia. Hereditary forms of PHPT include multiple endocrine neoplasia type 1 (MEN-1), type 2A (MEN-2A), type 4 (MEN-4), hyperparathyroidism-jaw tumour syndrome (HPT-JT), variants of familial hypocalciuric hypercalcemia (FHH) and familial isolated hyperparathyroidism (FIHP). Mutations in the following genes cause the development of MEN-1, MEN-2A, MEN4, HPT-JT: MEN1, RET, CDKN1B, CDC73, respectively. Variants of FHH are caused by mutations in CASR, AP2S1, GNA11. Gene(s) responsible for the development of the majority of FIHP cases remain unknown. Identification of hereditary forms of PHPT is important for patients and their first-degree relatives, as it allows defining the necessity of screening to reveal other components of the syndrome, in some cases determines the surgical approach to PHPT, and the risk of development of the disease in offsprings. This article provides information on hereditary syndromes associated with PHPT and special features of PHPT in each syndrome.

Ailesel hipokalsiürik hiperkalsemi, kalsiyum duyarlı reseptörleri kodlayan gende inaktive edici heterozigot mutasyonlar nedeniyle oluşan, kalsiyum metabolizmasını etkileyen ve genellikle benign seyreden kalıtımsal bir hastalıktır. Primer hiperparatiroidinin ayırıcı tanısında mutlaka düşünülmelidir. Dış merkezde toksik nodüler guatr ve primer hiperparatiroidi tanılarıyla cerrahi kararı alınan olgumuzun kliniğimizce yapılan değerlendirmesinde kalsiyum metabolizmasını etkileyebilecek furosemid alımı kesildi ve hipertiroidisi düzeltildi. Tekrar değerlendirmede ılımlı hiperkalsemi, sınırda yüksek parathormon düzeyleri ve idrarla günlük kalsiyum atılımının belirgin düşüklüğü nedeniyle ailesel hipokalsiürik hiperkalsemi olabileceği düşünüldü. Çocuklarında kalsiyum metabolizmasında benzer laboratuvar bulguları saptanması üzerine tanı doğrulandı. Kalsiyum metabolizmasını, etkilenebileceği diğer faktörleri düzelttikten sonra değerlendirmek klinisyenleri sıklıkla yanlış tanıdan uzaklaştıracaktır. Hiperkalsemiye tanısal yaklaşımda ve primer hiperparatiroidi ayırıcı tanısında ailesel hipokalsiürik hiperkalsemiyi akılda tutmak gereksiz cerrahinin önüne geçecektir.

Familial Hypocalciuric Hypercalcemia is a generally benign disorder caused by heterozygous inactivating mutations in the Calcium-Sensing-Receptor gene resulting in altered calcium metabolism. It should be considered in differential diagnosis of primary hyperparathyroidism. Our case whom was diagnosed as toxic nodular goitre and primary hyperparathyroidism and suggested surgical treatment in another clinical center was evaluated in our out-patient clinic. Furosemid treatment which may affect calcium metabolism was stopped and medical therapy for hyperthyroidism was given. During follow-up the patient was considered as familial hypocalciuric hypercalcemia because of mild hypercalcemia, borderline elevated parathormone levels and significantly decreased daily urinary calcium excretion. The diagnosis was confirmed with the determination of similar laboratory findings for calcium metabolism in her children. In conclusion, evaluating the calcium metabolism after correcting the other factors and keeping familial hypocalciuric hypercalcemia in mind while diagnostic approach to hypercalcemia and differentially diagnosis of primary hyperparathyroidism may prevent unnecessary surgery. [Cukurova Med J 2013; 38(4.000): 765-769]

Objective to report a case of familial hypocalciuric hypercalcemia (FHH) in an older patient and highlight the diagnostic challenges in geriatric populations.Case presentation We report the diagnosis of FHH in an 88-year-old polypathological patient with hypercalcemia discovered during a check-up for cardiac decompensation. Despite a confusing clinical presentation with gout symptoms, including repeated episodes of knee arthritis, persistent hypercalcemia conducted further investigations. Biological tests excluded primary or hyperparathyroidism and malignancy-related hyperparathyroidism, confirming the diagnosis of FHH through the detection of an inhibitory mutation in the calcium-sensing receptor gene.Conclusion This case suggests to clinicians the possibility of FHH in older patients with unexplained hypercalcemia. In geriatric patients, the diagnosis is complicated because of the poly-pathology: here hypercalcemia was associated with a confusing gout crisis, which was triggered by diuretic treatment for heart failure.

We report a patient with familial hypocalciuric hypercalcemia (FHH) associated with primary hyper-parathyroidism (PHPT) and incidental papillary thyroid carcinoma. The patient showed hypercalcemia, high parathyroid hormone (PTH) levels and low urinary calcium excretion. A computed tomography (CT) scan revealed an enlarged parathyroid gland. Ultrasonography (US) and aspiration cytology revealed microcarcinoma of the left lobe of the thyroid gland. Screening studies of his family revealed that four of five family members had hypocalciuric hypercalcemia and normal PTH level. Sequencing analysis of the calcium sensing receptor gene revealed a novel heterozygous mutation (3193delA) in the patient and his family members with hypercalcemia, but one with normocalcemia. The patient underwent total thyroidectomy, central node dissection and extirpation of the enlarged parathyroid gland. Surgery is not indicated for FHH; however, FHH may be accompanied with parathyroid adenoma causing PHPT, as reported here, for which surgical treatment is indicated.

The recently cloned extracellular calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays an essential role in the regulation of extracellular calcium homeostasis. This receptor is expressed in all tissues related to this control (parathyroid glands, thyroid C-cells, kidneys, intestine and bones) and also in tissues with apparently no role in the maintenance of extracellular calcium levels, such as brain, skin and pancreas. The CaR amino acid sequence is compatible with three major domains: a long and hydrophilic aminoterminal extracellular domain, where most of the activating and inactivating mutations described to date are located and where the dimerization process occurs, and the agonist-binding site is located, a hydrophobic transmembrane domain involved in the signal transduction mechanism from the extracellular domain to its respective G protein, and a carboxyterminal intracellular tail, with a well-established role for cell surface CaR expression and for signal transduction. CaR cloning was immediately followed by the association of genetic human diseases with inactivating and activating CaR mutations: familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism are caused by CaR-inactivating mutations, whereas autosomal dominant hypoparathyroidism is secondary to CaR-activating mutations. Finally, we will comment on the development of drugs that modulate CaR function by either activating (calcimimetic drugs) or antagonizing it (calcilytic drugs), and on their potential therapeutic implications, such as medical control of specific cases of primary and uremic hyperparathyroidism with calcimimetic drugs and a potential treatment for osteoporosis with a calcilytic drug.