BACKGROUND: This case report presents a history of familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC). The patient was admitted to the hospital with hypertensive encephalopathy. FHHNC is a rare autosomal recessive disease caused by mutations in CLDN16 or CLDN19, resulting in insufficient magnesium and calcium kidney reabsorption. FHHNC manifestation starts in childhood, and over the years, its development leads to nephrocalcinosis and, consequently, chronic kidney disease (CKD), which is not slowed by routine administration of magnesium and thiazide diuretics. Ultimately, all FHHNC patients need kidney replacement therapy (KRT). CASE PRESENTATION: The patient was a 28-year-old male diagnosed with FHHNC and admitted to the emergency room due to hypertensive encephalopathy. The current situation was the patient\'s second hospitalization related to a hypertensive emergency caused by under-dialysis. Despite the signs of insufficient functioning of peritoneal dialysis (PD) (the primary chosen form of KRT), the patient refused the proposed conversion to hemodialysis (HD). Symptoms observed upon admission included disorientation, anxiety, and severe hypertension, reaching 213/123 mmHg. Due to his clinical condition, the patient was transferred to the intensive care unit (ICU), where the introduction of continuous veno-venous hemodiafiltration and hypotensive therapy stabilized blood pressure. Within the next few days, his state improved, followed by discharge from ICU. Eventually, the patient agreed to transition from PD to in-center HD. At the time, he was qualified for kidney transplantation, waiting for a compatible donation. CKD and dialysis are factors that significantly affect a patient\'s quality of life, especially in young patients with congenital diseases like FHHNC. CONCLUSIONS: For the aforementioned reasons, appropriate education and psychological support should be ensured to avoid the harmful effects of therapy non-compliance.
UNASSIGNED: https://www.europeanreview.org/wp/wp-content/uploads/Graphical-abstract-1.pdf.

Absorptive hypercalciuria (AH) is a prevalent cause of kidney stones, and the adenylate cyclase 10 (ADCY10) gene is a rare causative gene of AH. This study aims to investigate the genotypic and phenotypic characteristics of patients with AH caused by ADCY10 gene mutations. Whole-exome sequencing and Sanger sequencing were performed on the probands and their family members, respectively. Clinical and genetic data of patients with AH caused by ADCY10 gene mutations were collected and analysed retrospectively from the present study and published literature. Two female patients (6 years old and 1 year old) with multiple bilateral kidney stones were found to have a heterozygous c.3304T>C mutation and a heterozygous c.1726C>T mutation in the ADCY10 gene. Urinary metabolite analysis revealed that urine calcium / creatinine ratios were 0.95 mmol/mmol and 1.61 mmol/mmol, respectively. Both patients underwent thiazide intake postoperatively, and upon reexamination, urine calcium decreased to within the normal range. A total of 61 patients with AH were reported from previous and present studies. The sex ratio was 7:5 for males to females, and the mean age of onset was 23.61±20.08 years. A total of 16 ADCY10 gene mutations were identified, including seven missense (43.75%), five splicing (31.25%), two frameshift (12.50%) and two nonsense mutations (12.50%). Only two cases were identified as homozygous mutations (c.1205_1206del), and the others were heterozygous mutations. In summary, we identified two novel ADCY10 gene candidate pathogenic variants in Chinese pediatric patients, which expands the mutational spectrum of the ADCY10 gene and provides a potential diagnostic and therapeutic target.

The parathyroid gland is responsible for the synthesis and secretion of parathyroid hormone, which is synthesized and released at an inverse relationship to the level of ionized calcium in the blood. Primary hyperparathyroidism affects women more than men. There are various causes for hyperparathyroidism-induced hypercalcemia and the most common cause is parathyroid adenoma. A less common cause of vitamin D-mediated parathyroid hormone-independent hypercalcemia is the loss of function mutation of the CYP24A1 gene. The CYP24A1 gene encodes the vitamin D 24-hydroxylase enzyme, responsible for hydroxylating the active form of vitamin D into an inactive form, and mutations in the CY24A1 gene can lead to elevated active vitamin D metabolite levels. It can result in hypercalcemia and hypercalciuria-related complications. We present a case of a 72-year-old male patient referred to the endocrine clinic, who had repeated treatments for hypercalcemia and recurrent renal calculi. He underwent ultrasound, computerized tomography, and sestamibi scans, all reported as normal. Following this, the patient underwent a positron emission tomography (PET) scan, which was also normal. He then finally underwent genetic testing and tested positive for the CYP24A1 gene. He was started on fluconazole 50mg once a day and cinacalcet 30mg twice with normalization of calcium level. Three of his family members also tested positive for the condition.

Bartter syndrome is a rare, salt-wasting tubulopathy with impaired ion reabsorption in the ascending limb of the loop of Henle, which results in hypokalemia, hypochloremia, and hypercalciuria. It usually presents in neonates, with vomiting, dehydration, and failure to thrive. It results from mutations in several genes, including KCNJ1, CLCNKB, CLCNKA, BSND, and ROMK, which encode ion transporters. We report a rare presentation of adult-onset Bartter syndrome. In this case, a 27-year-old man presented to the hospital with upper and lower limb weakness. Bartter syndrome was suspected based on serum electrolytes assessment and arterial blood gas analysis. The patient was initiated on potassium chloride (KCL) infusion and potassium chloride syrup to correct hypokalemia.

OBJECTIVE: Autosomal dominant hypocalcaemia 1 (ADH1) is a rare autosomal dominant genetic disease, due to the activating mutations of the calcium-sensing receptor (CASR) gene. The current paper presents a severe case of ADH1 with intellectual backwardness, and systematically reviews the reported 17 ADH1 patients in China.
METHODS: A 7 years old boy with recurrent seizures over 1 year was admitted at Yuying children\' hospital, the clinical centre of south province of Zhejiang. Auxiliary examinations demonstrated hypocalcaemia, hyperphosphatemia, hypomagnesemia, hypercalciuria, low parathyroid hormone (PTH), basal ganglia calcifications, normal range of serum creatinine, and 25-hydroxyvitamin D. Wechsler\'s intelligence test result indicated intellectually backward. The patient\'s genotype found a heterozygous variant in CASR gene, c.T416C p. (Ile139Thr). This article also systematically reviews the literatures on ADH1 in China and summarises the clinical characteristics and treatment.
CONCLUSIONS: ADH1 can be a cause of idiopathic hypoparathyroidism. Recognition and rational treatment is important for symptom improvement and reducing high potential adverse effects.

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BACKGROUND: Familial hypocalciuric hypercalcaemia (FHH) is a rare, inherited disorder of extracellular calcium sensing. It is clinically characterised by mild to moderate parathyroid hormone dependent hypercalcaemia, an autosomal dominant pattern of inheritance, and a normal to reduced urinary calcium excretion in spite of high serum calcium.
METHODS: We report two cases of FHH in a family caused by a novel pathogenic missense variant in the CaSR gene, p. His41Arg. Case 1, describes a 17 year old female with no significant past medical history, admitted with acute appendicitis requiring laparoscopic appendectomy and reporting a six month history of polydipsia. Routine investigations were significant for hypercalcaemia, corrected calcium 3.19 mmol/L (2.21-2.52mmol/L), elevated parathyroid hormone of 84pg/ml (15-65pg/ml) and a low 24-hour urine calcium of 0.75mmol/24 (2.50-7.50mmol/24). She was initially managed with intravenous fluids and Zolendronic acid with temporary normalisation of calcium though ultimately required commencement of Cinacalcet 30 mg daily for persistent symptomatic hypercalcaemia. Genetic analysis was subsequently positive for the above variant. Case 2, a 50-year-old female, was referred to the endocrine outpatient clinic for the management of type 2 diabetes and reported a longstanding history of asymptomatic hypercalcaemia which had not been investigated previously. Investigation revealed hypercalcaemia; corrected calcium of 2.6 mmol/L (reference range: 2.21-2.52 mmol/L); PTH of 53.7ng/L (reference range: 15-65 ng/L) and an elevated 24-hour urine calcium of 10 mmol/24 (2.50-7.50 mmol/24hr) with positive genetic analysis and is managed conservatively. Despite sharing this novel mutation, these cases have different phenotypes and their natural history is yet to be determined. Two further relatives are currently undergoing investigation for hypercalcaemia and the family have been referred for genetic counselling.
CONCLUSIONS: Accurate diagnosis of FHH and differentiation from classic primary hyperparathyroidism can be challenging, however it is essential to avoid unnecessary investigations and parathyroid surgery. Genetic analysis may be helpful in establishing a diagnosis of FHH in light of the biochemical heterogeneity in this population and overlap with other causes of hypercalcaemia.

25-Hydroxyvitamin D 24-hydroxylase (CYP24A1) deficiency is a rare cause of autosomal recessive infantile hypercalcemia due to vitamine D hypersensitivity.
We report the case of a 2-year-old boy who presented with severe hypercalcemia-hypercalciuria and a bilateral nephrocalcinosis. Laboratory investigations detected a collapsed parathormone and a highly elevated 1α,25-dihydroxycholecalciferol along with an increased phosphate excretion (hypophosphatemia and hyperphosphaturia). An adapted management with two courses of palmidronic acid and an eviction of vitamin D and calcium allowed to stabilize him. A homozygous p.Leu409Ser pathogenic variant on CYP24A1 gene resulting in a collapsed 25-Hydroxyvitamin D24-hydroxylase activity was found. A normal development is possible with a meticulous clinical, biological and nutritional management and monitoring.
Vitamin D hypersensitivity is challenging during childhood, especially due to the need to avoid vitamin D while requiring a close nutritional monitoring to maintain a normal growth. Biomarkers such as vitamin D metabolite ratio and 24,25(OH)2D3 along with ionized calcium and nutritional management can contribute to properly follow patients with vitamin D hypersensitivity.
Le déficit en 25-hydroxyvitamine D 24-hydroxylase (CYP24A1) est une cause rare d’hypercalcémie infantile autosomique récessive due à une hypersensibilité à la vitamine D.
Nous rapportons le cas d’un garçon de 2 ans qui a présenté une hypercalcémie-hypercalciurie sévère et une néphrocalcinose bilatérale. Les examens de laboratoire ont détecté une parathormone effondrée et un 1α,25-dihydroxycholécalciférol très élevé ainsi qu’une excrétion accrue de phosphate (hypophosphatémie et hyperphosphaturie). Une prise en charge adaptée avec deux cures d’acide palmidronique et une éviction de la vitamine D et du calcium a permis de le stabiliser. Un variant pathogène homozygote p.Leu409Ser sur le gène CYP24A1 entraînant un effondrement de l’activité de la 25-hydroxyvitamine D24-hydroxylase a été retrouvé. Un développement normal est possible avec une prise en charge et un suivi clinique, biologique et nutritionnel méticuleux.
L’hypersensibilité à la vitamine D est un défi pendant l’enfance, notamment en raison de la nécessité d’éviter la vitamine D tout en exigeant un suivi nutritionnel étroit pour maintenir une croissance normale. Les biomarqueurs tels que le rapport des métabolites de la vitamine D et la 24,25(OH)2D3, ainsi que le calcium ionisé et la gestion nutritionnelle peuvent contribuer à un suivi adéquat des patients souffrant d’hypersensibilité à la vitamine D.

Autosomal dominant hypocalcemia type 1 (ADH1) is a rare inherited disorder characterized by hypocalcemia with low parathyroid hormone (PTH) levels and high urinary calcium. Its clinical presentation varies from mild asymptomatic to severe hypocalcemia. It is caused by gain-of-function mutations in the calcium-sensing receptor gene (CASR) which affect PTH secretion from the parathyroid gland and calcium resorption in the kidney. Here, we describe a case who presented with symptoms of recurrent seizure caused by hypocalcemia with a novel CASR variant. We comprehensively analyzed the phenotypic features of this presentation and reviewed the current literature to better understand clinical manifestations and the genetic spectrum.

Autosomal dominant hypocalcemia (ADH) is characterized by hypocalcemia and inappropriately low PTH concentrations. ADH type 2 (ADH2) is caused by a heterozygous gain-of-function mutation in GNA11 that encodes the subunit of G11, the principal G protein that transduces calcium-sensing receptor signaling in the parathyroid. Clinical features related to hypocalcemia in ADH2 range from asymptomatic to tetany and seizures. We report the clinical and molecular analysis of an infant with ADH2. Exome sequencing identified a de novo heterozygous missense variant, c. G548C (p. Arg183Pro) in GNA11. This is the youngest Korean case to be diagnosed with ADH 2. In addition, we summarized the literature related to eight mutations in GNA11 from 10 families.