Atlantoaxial Instability due to Os Odontoideum in a Child with Christianson Syndrome.

Introduction: Christianson syndrome is a rare neurodevelopmental disorder associated with mutations in the SLC9A6 gene located on the chromosome X. It is characterized by intellectual disability, developmental delay, speech and language impairments, dysmorphic features, seizures, ataxia, and neurobehavioral problems. Case Presentation: A 5-year-old boy was presented with respiratory failure and then progressive muscle weakness in all four extremities. He manifested acquired microcephaly, intellectual disability, global developmental delay, distinct dysmorphic facial features, seizures, spastic tetraparesis, truncal hypotonia, speech impairment, failure to thrive, malnutrition, recurrent lung infections, self-mutilation, primary hyperparathyroidism, medullary nephrocalcinosis, and atlantoaxial instability due to os odontoideum. Brain magnetic resonance imaging revealed atlantoaxial instability due to os odontoideum, a narrow foramen magnum, myelopathy due to spinal cord compression, and cerebral and cerebellar atrophy. Discussion: This report highlights a significant contribution by introducing a child with Christianson syndrome describing atlantoaxial instability due to os odontoideum, a previously undocumented phenomenon. This report suggests a potential link between Christianson syndrome and atlantoaxial instability. In children with Christianson syndrome experiencing increased muscle weakness in all extremities during follow-up, consideration of underlying myelopathy due to os odontoideum is advised.

A case of enamel renal syndrome from a novel genetic mutation, multidisciplinary management and long-term prognosis.

Background: The heterogeneous features of enamel renal syndrome (ERS) make diagnosis and treatment challenging. The main symptoms are disturbed amelogenesis and nephrocalcinosis. Bi-allelic likely pathogenic (LP) or pathogenic (P) variants in FAM20A have been associated with the syndrome since 2012. Affected patients often receive extensive dental treatment because of deviant orofacial morphology. However, knowledge about long-term prognosis and treatment guidelines are still lacking. The complex nature of ERS might endanger both dental and general health. The purpose of this article is to highlight the risks of overlooking the symptoms of the syndrome, and to discuss management strategies, surveillance and prognosis. Case presentation: We report the management of a case with suspected ERS after initial dental treatment elsewhere with no adjustment for the syndrome. Dental treatment was revised and followed for 8 years. Complementary medical examinations were conducted, and ERS was genetically confirmed, revealing homozygosity for a LP c.755_757del, p.(Phe252del) variant in FAM20A. The nephrological investigation revealed medullary calcium deposits, normal renal function and hypophosphatemia. Urine analysis revealed hypocitraturia and hypocalciuria. Accordingly, the patient now medicates with potassium citrate to decrease the risk of progressive renal stone formation. Conclusion: We herein describe a patient with confirmed ERS with an 8-year follow-up. Diagnostic delay until adulthood led to complicated dental treatment. The results of nephrological investigations are presented. The importance of dental and medical multidisciplinary management in syndromic disorders affecting the formation of the enamel is also exemplified. The dental prognosis after rehabilitation is likely affected by anatomical variations and patient cooperation. The prognosis for renal function seems to be good. However, lifelong surveillance of renal function is recommended. Registration: The ethics committee in Uppsala, Sweden, determined that ethical approval was not necessary in this case (2019-04835). Informed consent was obtained from the participant in writing and is documented in the medical records.

Pectolinarigenin alleviates calcium oxalate-induced renal inflammation and oxidative stress by binding to HIF-1α.

Calcium oxalate (CaOx) crystals are the main constituents of renal crystals in humans and induce tubular lumen damage in renal tubules, leading to renal calcium deposition and kidney stone formation. Oxidative stress and inflammation play important roles in regulating calcium oxalate-induced injury. Here, we evaluated the efficacy in inhibiting oxidation and inflammation of pectinolinarigenin, a biologically active natural metabolite, in CaOx nephrocalcinosis and further explored its targets of action. First, we developed cellular and mouse models of calcium oxalate renal nephrocalcinosis and identified the onset of oxidative stress and inflammation according to experimental data. We found that pectolinarigenin inhibited this onset while reducing renal crystal deposition. Network pharmacology was subsequently utilized to screen for hypoxia-inducible factor-1α (HIF-1α), a regulator involved in the body's release and over-oxidation of inflammatory factors. Finally, molecular docking, cellular thermal shift assay, and other experiments to detect HIF-1α expression showed that pectolinarigenin directly combined with HIF-1α and prevented downstream reactive oxygen species activation and release. Our results indicate that pectolinarigenin can target and inhibit HIF-1α-mediated inflammatory responses and oxidative stress damage and be a novel drug for CaOx nephrocalcinosis treatment.

Prevalence, risk factors and effect of curative parathyroidectomy on nephrocalcinosis in Asian-Indian patients with symptomatic primary hyperparathyroidism.

Primary hyperparathyroidism (PHPT) is characterized by inappropriate secretion of parathyroid hormone, causing hypercalcemia and hypercalciuria, leading to renal stone diseases and nephrocalcinosis. The frequency, risk factors, and curative effect on nephrocalcinosis in post-parathyroidectomy have not been identified yet. Therefore, the present study evaluated the clinico-biochemical, radiological parameters and curative effect on nephrocalcinosis. A total of 583 PHPT patients were analysed in four groups viz. Group 1 (PHPT with nephrocalcinosis-98; 16.8%); Group 2 (PHPT with nephrolithiasis-227; 38.9%); Group 3 (PHPT with both nephrolithiasis and nephrocalcinosis-59; 10.1%); and Group 4 (PHPT without renal diseases-199, 34.1%). In the sub-group analysis, younger age (p ≤ 0.05), male gender (p ≤ 0.05), and hematuria (p ≤ 0.005) were significant in Group 1 vs. Group 4. Dysuria and low eGFR were significant in Group 1 vs. Group 2 (p ≤ 0.0005; p ≤ 0.05) and Group 1 vs. Group 4 (p ≤ 0.0005; p ≤ 0.0005). Polyuria (p ≤ 0.05; p ≤ 0.05, p ≤ 0.005), and gravluria (p ≤ 0.05; p ≤ 0.0005, p ≤ 0.005) were frequent in Group 1 vs. other groups. A significant difference was observed in S.Ca and, 24-hrs U.Ca in Group 1 vs. Group 2 {(12.2 (10.8-13.4) vs. 11.2 (10.7-12.4), p ≤ 0.05; 301 (189.5-465) vs. 180 (92.5-323.1), p ≤ 0.05} and Group 1 vs. Group 4 {(12.2 (10.8-13.4) vs. 11.4 (10.7-12.5), p ≤ 0.05 ; 301 (189.5-465) vs. 213 (110-360), p ≤ 0.0005}. Multivariate logistic regression showed gravluria [aOR = 9.2, p = 0.0001], S.Ca (aOR = 1.30, p = 0.003) and, 24-hrs U.Ca (aOR = 1.02, p = 0.042) to be independent predictors of nephrocalcinosis. Pre and post-operative assessment revealed decreased S. Ca levels [(11.9 ± 1.9) vs. (10.5 ± 1.0) mg/dL; p = 0.04] and complete radiological resolution (10.4%) in PHPT with nephrocalcinosis. Therefore, serum calcium, 24-hrs Urinary calcium, and gravluria were independent predictors of nephrocalcinosis with 10.4% showing complete radiological resolution post-operatively.

Effects of SLC34A3 or SLC34A1 variants on calcium and phosphorus homeostasis.

BACKGROUND: Variants in SLC34A1 and SLC34A2 genes, which encode co-transporters NaPi2a and NaPi2c, respectively, can lead to hypophosphatemia due to renal phosphate loss. This condition results in hypercalcitriolemia and hypercalciuria, leading to formation of kidney stones and nephrocalcinosis. Phenotype is highly variable. Management includes hyperhydration, dietary modifications, and/or phosphate supplementation. Thiazides and azoles may be used, but randomized studies are needed to confirm their clinical efficacy. METHODS: We conducted a retrospective study in the pediatric nephrology unit at Grenoble University Hospital from January 2010 to December 2023. The study aimed to describe clinical and biological symptoms of patients with confirmed SLC34A1 and SLC34A3 gene variants and their outcomes. RESULTS: A total of 11 patients (9 females) from 6 different families had variants in the SLC34A1 (5 patients) and SLC34A3 (6 patients) genes. Median age at diagnosis was 72 [1-108] months. Average follow-up duration was 8.1 ± 4.5 years. Presenting symptom was nephrocalcinosis (4 cases), followed by renal colic (3 cases). At diagnosis, 90% of patients had hypercalciuria and 45% had hypercalcitriolemia. Management included hyperhydration and dietary advice. All patients showed favorable outcomes with normal growth and school attendance. One patient with an SLC34A3 variant showed regression of nephrocalcinosis. Kidney function remained normal. CONCLUSION: Clinical and biological manifestations of SLC34 gene variants are highly variable, even among siblings; therefore, management must be personalized. Hygienic and dietary measures (such as hyperhydration, a low sodium diet, and age-appropriate calcium intake) result in favorable outcomes in most cases. Use of azoles (e.g., fluconazole) appears to be a promising therapeutic option.

Prevalence of kidney failure in adults diagnosed with hereditary tubulopathies.

BACKGROUND: Inherited tubulopathies are rare kidney diseases with few data available in the literature regarding their long-term renal prognosis. This study aimed to evaluate the prevalence of kidney failure in adults with confirmed genetic tubulopathy and to describe the corresponding clinical and genetic findings. METHODS: In this observational cohort study, we focused on genetic tubulopathies assumed to impact kidney function. In all adult patients genetically diagnosed in our laboratory between 2001 and 2019, we estimated Glomerular Filtration Rate (eGFR) at diagnosis using the Modification of diet in renal disease (MDRD) formula. Kidney failure was defined as an eGFR < 60 ml/min/1.73 m2. RESULTS: A total of 2145 patients underwent genetic testing, confirming a genetic tubulopathy in 1031 cases (48%). We identified 116 patients out of 885 with available data with kidney failure, mostly diagnosed with Dent disease and distal renal tubular acidosis (respectively, 31% and 20%), followed by familial hypomagnesemia with hypercalciuria and nephrocalcinosis and renal hypophosphatemia/infantile hypercalcemia. Renal prognosis appeared particularly impacted in familial hypomagnesemia with hypercalciuria and nephrocalcinosis and Dent disease, while preserved in Gitelman syndrome. CONCLUSION: In this cohort, 13% of adults with genetic tubulopathy had kidney failure at diagnosis, with this rate varying greatly according to tubulopathies and suggesting a significant impact on renal prognosis. Even in adults, genetic analyses yield a good diagnostic rate in selected patients, and should be performed as soon as possible, in order to improve the renal management of patients and their relatives.

CCDC158: A novel regulator in renal proximal tubular endocytosis unveiled through exome sequencing and interactome analysis.

Renal proximal tubular reabsorption of proteins and polypeptides is tightly regulated by a concerted action of the multi-ligand receptors with subsequent processing from the clathrin-coated pits to early/recycling and late endosomes and towards lysosomes. We performed whole exome-sequencing in a male patient from a consanguineous family, who presented with low- and intermediate molecular weight proteinuria, nephrocalcinosis and oligospermia. We identified a new potential player in tubular endocytosis, coiled-coil domain containing 158 (CCDC158). The variant in CCDC158 segregated with the phenotype and was also detected in a female sibling with a similar clinical kidney phenotype. We demonstrated the expression of this protein in kidney tubules and modeled its structure in silico. We hypothesized that the protein played a role in the tubular endocytosis by interacting with other endocytosis regulators, and used mass spectrometry to identify potential interactors. The role of CCDC158 in receptor-mediated endocytosis was further confirmed by transferrin and GST-RAP trafficking analyses in patient-derived proximal tubular epithelial cells. Finally, as CCDC158 is known to be expressed in the testis, the presence of oligospermia in the male sibling further substantiated the pathogenic role of the detected missense variant in the observed phenotype. In this study, we provide data that demonstrate the potential role of CCDC158 in receptor-mediated endocytosis, most likely by interaction with other endocytosis-related proteins that strongly correlate with the proximal tubular dysfunction phenotype as observed in the patients. However, more studies are needed to fully unravel the molecular mechanism(s) in which CCDC158 is involved.

X-linked hypophosphatemic rickets and nephrocalcinosis: clinical characteristics of a single-center pediatric cohort in North America before and after burosumab.

Background: X-linked hypophosphatemic rickets (XLH) is a rare genetic disease characterized by inappropriately elevated circulating fibroblast growth factor 23 (FGF-23) and subsequent urinary phosphate wasting. The primary clinical manifestations of XLH include short stature, lower extremity bowing, dental abscesses, and rickets. Historical treatment includes phosphate and vitamin D supplementation, but recently, targeted therapy with burosumab has gained widespread acceptance. Burosumab is an FGF-23 blocking antibody. Conventional therapy options have been associated with the development of nephrocalcinosis (NC), with reported rates varying between 33% and 80% in XLH patients. Previous studies have noted that the phosphate supplementation dose correlates with the presence of NC, although this finding is not consistent across studies. It remains unclear whether nephrocalcinosis occurs in patients now treated with burosumab. Our aim was to identify XLH-associated nephrocalcinosis risk factors in our cohort of children with XLH and provide an updated analysis in the era of burosumab. Methods: We identified 13 children with XLH who received routine medical care for XLH at our institution between 2015 and 2023. All were initially treated with conventional therapy and were transitioned to burosumab either upon its US Food and Drug Administration (FDA) approval in 2018 or at 6 months of age if this occurred after 2018. All patients were routinely monitored and this included laboratory tests and renal ultrasonography. Phosphate and calcitriol dosages were regularly adjusted to minimize serum and urinary laboratory abnormalities. Burosumab was administered according to its FDA package insert directions. Medication doses and laboratory values were analyzed between the group with NC and the group without NC. Results: Three patients were noted to have evidence of NC within the study timeline. Two children developed NC while receiving conventional therapy and one while prescribed burosumab. None of the variables, including a positive family history of XLH, average age at diagnosis of XLH, duration or dosage of treatment with conventional therapy, average age at the initiation of burosumab, and all measured laboratory values, were significantly different between the groups with and without NC. Female sex was the only identified significant risk factor for a diagnosis of XLH-associated NC. Conclusion: XLH-associated NC remains a clinical concern even with modern treatment, although the traditional risk factors (dose of phosphate supplements and degree of urinary phosphate excretion) may not always correlate with the onset of nephrocalcinosis. XLH patients receiving burosumab, which has been hypothesized to eliminate the risk factors for NC, can still develop NC. It is important to continue screening patients treated with burosumab for nephrocalcinosis. In addition, more research is needed to better understand the risk factors that cause XLH-associated NC and determine whether children with XLH never exposed to conventional therapy will develop NC.

Nephrocalcinosis and kidney function in children and adults with X-linked hypophosphatemia: baseline results from a large longitudinal study.

BACKGROUND: In patients with X-linked hypophosphatemia (XLH), conventional therapy with oral phosphate salts and active vitamin D has been associated with nephrocalcinosis. However, the nature of the relationships among XLH, its treatment, nephrocalcinosis, and kidney function remain poorly understood. METHODS: Renal ultrasounds were performed and glomerular filtration rates were estimated (eGFR) at baseline in burosumab-naïve patients with XLH who participated in burosumab clinical trials (NCT02181764, NCT02526160, NCT02537431, NCT02163577, NCT02750618, NCT02915705) or enrolled in the XLH Disease Monitoring Program (XLH-DMP; NCT03651505). In this cross-sectional analysis, patient, disease, and treatment characteristics were described among patients with and without nephrocalcinosis. RESULTS: The analysis included 196 children (mean [SD] age 7.6 [4.0] yr) and 318 adults (40.3 [13.1] yr). Mean (SD) height z-score was -1.9 (1.2) for children and -2.3 (1.7) for adults. Nearly all children (97%) and adults (94%) had previously received conventional therapy. Nephrocalcinosis was detected in 22% of children and 38% of adults. In children, reduced eGFR <90 mL/min/1.73 m2 was more prevalent in those with nephrocalcinosis (25%) than in those without (11%), a finding that was not observed in adults. Children with nephrocalcinosis had lower mean values of TmP/GFR (p<.05), serum 1,25(OH)2D (p<.05), and eGFR (p<.001) and higher mean serum calcium concentrations (p<.05) than did those without nephrocalcinosis. Adults with nephrocalcinosis had lower mean serum phosphorus (p<.01) and 1,25(OH)2D (p<.05) concentrations than those without. Exploratory logistic regression analyses revealed no significant associations between the presence of nephrocalcinosis and other described patient or disease characteristics. CONCLUSIONS: Nephrocalcinosis was observed in nearly one-quarter of children and more than one-third of adults with XLH. Further study is needed to better understand the predictors and long-term consequences of nephrocalcinosis, with surveillance for nephrocalcinosis remaining important in the management of XLH.

Conventionally, patients with X-linked hypophosphatemia (XLH) were treated with phosphate and vitamin D taken by mouth. However, this therapy might lead to a buildup of calcium in the kidney, called nephrocalcinosis. Here, we tried to better understand how XLH, conventional therapy, nephrocalcinosis, and kidney function are related. Nephrocalcinosis was detected with kidney ultrasounds. Kidney function, called the estimated glomerular filtration rate (eGFR), was determined using blood levels of creatinine. Patients had been part of burosumab clinical trials or part of the XLH Disease Monitoring Program. Data were collected from patients before they received burosumab. The study included 196 children and 318 adults. Almost all children and adults had received conventional therapy. 22% of children and 38% of adults had nephrocalcinosis. Some lab values were different among patients with vs without nephrocalcinosis. Children with nephrocalcinosis had significantly greater loss of phosphate by the kidneys, lower blood levels of the active form of vitamin D (1,25(OH)2D), lower eGFR, and higher blood levels of calcium than those without nephrocalcinosis. Adults with nephrocalcinosis had significantly lower blood levels of phosphorus and 1,25(OH)2D concentrations than those without. It remains important to monitor patients with XLH for nephrocalcinosis. Further study is needed to better understand nephrocalcinosis.

Rare manifestations of sarcoidosis in a young boy.

Sarcoidosis is a chronic multisystem granulomatous disease of unknown etiology. It is rare in young children. A 9-year-old boy presented with failure to thrive, skin rashes, persistent fever, and respiratory symptoms since 5 years of age. Blood investigations done showed elevated serum calcium and angiotensin converting enzyme levels and biopsy of the rashes on the left shin revealed non-caseating granulomatous lesion. Computed tomography of chest revealed interstitial lung disease and examination of eyes showed bilateral uveitis. He also had sensorineural hearing impairment, nephrocalcinosis, and short stature. The patient was treated with oral steroids and mycophenolate mofetil. At follow up, there was improvement in his systemic features including rashes and arthritis. Early detection, diagnosis, and appropriate treatment of sarcoidosis are vital for disease control and to avoid morbidity.

Clinical, Biochemical and Surgical Outcomes of Primary Hyperparathyroidism in the Present Era: A Prospective Study From a Tertiary Care Hospital.

Introduction Primary hyperparathyroidism (PHPT) has undergone a considerable change from being symptomatic to asymptomatic. This is the first large study from North India to study the clinical and biochemical features and surgical outcomes in the present era. Study design This is a cross-sectional study that was conducted in the Department of Endocrinology (SKIMS) from February 2021 to December 2022, in which 103 patients diagnosed with PHPT were included. Evaluation included measurement of total calcium, phosphorus, alkaline phosphate, intact parathyroid hormone, 25-hydroxy vitamin, 24-hour urinary calcium, radiological survey of hands and skull, Dual Energy X-ray absorptiometry, and ultrasonography (USG) of the abdomen. USG neck and technetium-99m sestamibi scans were used for preoperative localization; however, in cases of discordance between these investigations or suspicions of multi-glandular disease, four-dimensional computerized tomography of the neck was used. Patients were subjected to surgery according to the guidelines and monitored post-surgery for complications like hypocalcemia and hungry bone syndrome and to document the cure. Results The mean age of patients was 42.8±14.73 years, with a female-to-male ratio of 4.4:1. The mean eGFR of patients was 99.1±30.87 ml/min, with 55 (53.4%) of them having renal disease. Osteoporosis and fractures were present in 41 (39.8%) and 5 (4.8%) patients, respectively. Cholelithiasis and pancreatitis were present in 25 (24.3%) and 5 (4.9%) patients, respectively. Hypertension (HTN) and diabetes mellitus (DM) were the commonest comorbidities, which were present in 34 (33.1%) and 15 (14.5%) patients, respectively. Mean preoperative levels of calcium, phosphorus (PO4), alkaline phosphate (ALP), intact parathyroid hormone (iPTH), 25(OH)vitamin D, and 24-hour urinary calcium were 12.1 mg/dl, 2.35 mg/dl, 210.2 U/L, 332.9 pg/ml, 25.7 ng/ml, and 452.1 mg/day, respectively. The most common type was right inferior parathyroid adenoma, present in 45 cases (43.7%), followed by left inferior parathyroid adenoma in 31 cases (30.1%). A total of 75 patients (72.8%) underwent minimally invasive parathyroidectomy, with 68 patients (90.7%) achieving a biochemical cure. The mean adenoma weight was 3.19±2.25 g. There was no statistically significant correlation (r) between preoperative biochemical parameters and adenoma weight. Conclusion Despite improvements in imaging and the easy availability of immunoassays for early diagnosis, renal disease continued to be the most common presentation, followed by skeletal involvement in our population. In developing countries like India, any patient presenting with nephrolithiasis or nephrocalcinosis, low bone mass, or fragility fractures should be evaluated for PHPT.

Hypokalemia in a young man think Bartter syndrome type 3.

Background: Bartter syndrome is an autosomal recessive salt reabsorption disorder that results in decreased extracellular fluid volume with low/normal blood pressure. Case presentation: A 17-year-old boy with polydipsia, polyuria, weakness in the lower limbs, and ataxic gait. His Laboratory test shows hypokalemia; hypochloremia, hypomagnesemia and metabolic alkalosis. The authors' patient was managed by fluid and electrolyte replacement, which is essential in emergency management. Conclusion: Bartter syndrome is difficult to treat, and currently, there is no complete cure. The overall prognosis depends on the extent of receptor dysfunction, and despite these facts, most patients can live a normal life if they strictly follow their treatment plan.

ABCD syndrome, an uncommon cause of hypercalcemia in pediatrics. / Síndrome ABCD, una causa infrecuente de hipercalcemia en pediatría.

ABCD syndrome (ABnormal Calcium, Calcinosis, and Creatinine in Down syndrome) is characterized by an association of hypercalcemia, hypercalciuria, nephrocalcinosis, and impaired kidney function in patients with Down syndrome. Only 7 cases have been published worldwide, although it is believed to be underdiagnosed. This report describes 2 new patients with ABCD syndrome and compares them with the cases reported to date. Although it is a rare cause of pediatric hypercalcemia, it should be considered in children with Down syndrome once other more common etiologies have been ruled out. Once this diagnosis is confirmed, the recommended treatment is to reduce dietary calcium intake and work with an interdisciplinary team to maintain an adequate calorie and protein intake.

El síndrome ABCD (por sus siglas en inglés, ABnormal Calcium, Calcinosis and Creatinine in Down syndrome) se caracteriza por la asociación de hipercalcemia, hipercalciuria, nefrocalcinosis y alteración de la función renal en pacientes con síndrome de Down. Existen solo 7 casos previamente publicados en el mundo, aunque se cree que está subdiagnosticado. En este reporte, presentamos 2 nuevos pacientes con este síndrome y realizamos una comparación con los casos informados hasta el momento. Si bien es una causa rara de hipercalcemia pediátrica, debe considerarse en niños con síndrome de Down una vez descartadas otras etiologías más frecuentes. Al confirmarse este diagnóstico, el tratamiento recomendado es la reducción de calcio en la dieta, trabajando de manera interdisciplinaria para mantener un aporte calórico proteico adecuado.

Fanconi-Bickel syndrome complicated by nephrocalcinosis and GFR decline.

Fanconi-Bickel syndrome (FBS) is a rare genetic disorder of carbohydrate metabolism due to pathogenic variants in SLC2A2, a gene encoding glucose transporter 2 (GLUT2), which leads to accumulation of glycogen in the kidney and liver. While consequential complex proximal tubular dysfunction is well acknowledged in the literature, long-term trajectories of kidney function in patients with FBS have not been well characterized, and kidney biopsy is performed infrequently. Here, we report on a patient with FBS followed from infancy through young adulthood who presented early on with hypercalciuria, phosphaturia, and hypophosphatemia, complicated by chronic kidney disease development during childhood. Kidney biopsy, in addition to a widespread glycogen accumulation in proximal tubular epithelial cells, demonstrated medullary nephrocalcinosis. Screening for nephrocalcinosis may be warranted in pediatric patients with FBS, along with close surveillance of their kidney function.

Antenatal presentation and early postnatal treatment of infantile hypercalcemia type 2.

Infantile hypercalcemia (IH) is a rare genetic disorder characterized by hypercalcemia, hypercalciuria, low parathyroid hormone, and nephrocalcinosis during the first months of life. Biallelic variants in the genes CYP24A1 and SCL34A1 cause IH1 and 2, respectively. We present the case of a newborn with an antenatal diagnosis of IH2 due to the identification of echogenic, yet normal-sized kidneys at 23 weeks gestation. Trio whole-exome sequencing initially identified only a heterozygous pathogenic variant in SLC34A1. Re-analysis of the exome data because of the clinical suspicion of IH2 revealed a 21-basepair deletion in trans that had initially been filtered out because of its high allele frequency. The diagnosis of IH2 enabled postnatal screening for hypercalcemia, present already at week 1, resulting in early treatment with phosphate supplementation and vitamin D avoidance. In the subsequent course, biochemical parameters were normalized, and the patient showed no obvious clinical complications of IH2, apart from the nephrocalcinosis.

Infantile hypercalcemia type 1 (HCINF1): a rare disease resulting in nephrolithiasis and nephrocalcinosis caused by mutations in the vitamin D catabolic enzyme, CYP24A1.

Infantile hypercalcemia type 1 (HCINF1), formerly known as Lightwood syndrome, is a subtype of hypercalcemia caused by loss-of-function biallelic mutations in the vitamin D catabolic enzyme, CYP24A1, which 24-hydroxylates the hormone 1,25-(OH)2D3. This short review focuses on the main features of the HCINF1 disease; emerging knowledge of the structure and function of the cytochrome P450, CYP24A1 and the location of inactivating mutations; the development of a rapid LC-MS/MS-based laboratory test for defective 24-hydroxylation; and future implications for bioanalytical assay and treatment of all types of vitamin D-related hypercalcemic conditions.

Diagnosis and management of primary hyperoxalurias: best practices.

The primary hyperoxalurias (PH 1, 2, and 3) are rare autosomal recessive disorders of glyoxylate metabolism resulting in hepatic overproduction of oxalate. Clinical presentations that should prompt consideration of PH include kidney stones, nephrocalcinosis, and kidney failure of unknown etiology, especially with echogenic kidneys on ultrasound. PH1 is the most common and severe of the primary hyperoxalurias with a high incidence of kidney failure as early as infancy. Until the recent availability of a novel RNA interference (RNAi) agent, PH care was largely supportive of eventual need for kidney/liver transplantation in PH1 and PH2. Together with the Oxalosis and Hyperoxaluria Foundation, the authors developed a diagnostic algorithm for PH1 and in this report outline best clinical practices related to its early diagnosis, supportive treatment, and long-term management, including the use of the novel RNAi. PH1-focused approaches to dialysis and kidney/liver transplantation for PH patients with progression to chronic kidney disease/kidney failure and systemic oxalosis are suggested. Therapeutic advances for this devastating disease heighten the importance of early diagnosis and informed treatment.

Apparent mineralocorticoid excess in Israel: a case series and literature review.

BACKGROUND AND OBJECTIVE: Apparent mineralocorticoid excess (AME) syndrome is an ultra-rare autosomal-recessive tubulopathy, caused by mutations in HSD11B2, leading to excessive activation of the kidney mineralocorticoid receptor, and characterized by early-onset low-renin hypertension, hypokalemia, and risk of chronic kidney disease (CKD). To date, most reports included few patients, and none described patients from Israel. We aimed to describe AME patients from Israel and to review the relevant literature. DESIGN: Retrospective cohort study. METHODS: Clinical, laboratory, and molecular data from patients' records were collected. RESULTS: Five patients presented at early childhood with normal estimated glomerular filtration rate (eGFR), while 2 patients presented during late childhood with CKD. Molecular analysis revealed 2 novel homozygous mutations in HSD11B2. All patients presented with severe hypertension and hypokalemia. While all patients developed nephrocalcinosis, only 1 showed hypercalciuria. All individuals were managed with potassium supplements, mineralocorticoid receptor antagonists, and various antihypertensive medications. One patient survived cardiac arrest secondary to severe hyperkalemia. At last follow-up, those 5 patients who presented early exhibited normal eGFR and near-normal blood pressure, but 2 have hypertension complications. The 2 patients who presented with CKD progressed to end-stage kidney disease (ESKD) necessitating dialysis and kidney transplantation. CONCLUSIONS: In this 11-year follow-up report of 2 Israeli families with AME, patients who presented early maintained long-term normal kidney function, while those who presented late progressed to ESKD. Nevertheless, despite early diagnosis and management, AME is commonly associated with serious complications of the disease or its treatment.

Review of childhood genetic nephrolithiasis and nephrocalcinosis.

Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and economic burden. The etiology of NL and NC is multifactorial and includes both environmental components and genetic components, with multiple studies showing high heritability. Causative gene variants have been detected in up to 32% of children with NL and NC. Children with NL and NC are genotypically heterogenous, but often phenotypically relatively homogenous, and there are subsequently little data on the predictors of genetic childhood NL and NC. Most genetic diseases associated with NL and NC are secondary to hypercalciuria, including those secondary to hypercalcemia, renal phosphate wasting, renal magnesium wasting, distal renal tubular acidosis (RTA), proximal tubulopathies, mixed or variable tubulopathies, Bartter syndrome, hyperaldosteronism and pseudohyperaldosteronism, and hyperparathyroidism and hypoparathyroidism. The remaining minority of genetic diseases associated with NL and NC are secondary to hyperoxaluria, cystinuria, hyperuricosuria, xanthinuria, other metabolic disorders, and multifactorial etiologies. Genome-wide association studies (GWAS) in adults have identified multiple polygenic traits associated with NL and NC, often involving genes that are involved in calcium, phosphorus, magnesium, and vitamin D homeostasis. Compared to adults, there is a relative paucity of studies in children with NL and NC. This review aims to focus on the genetic component of NL and NC in children.