Nicotinamide treatment in a murine model of familial tumoral calcinosis reduces serum Fgf23 and raises heart calcium

Mutations in the GALNT3 gene result in familial tumoral calcinosis, characterized by persistent hyperphosphatemia and ectopic calcific masses in soft tissues. Since calcific masses often recur after surgical removal, a more permanent solution to the problem is required. Nicotinamide is reported to lower serum phosphate by decreasing sodium-dependent phosphate co-transporters in the gut and kidney. However, its effectiveness in tumoral calcinosis remains unknown. In this study, we investigated nicotinamide as a potential therapy for tumoral calcinosis, using a murine model of the disease-Galnt3 knockout mice. Initially, five different doses of nicotinamide were given to normal heterozygous mice intraperitoneally or orally. Treatment had no effect on serum phosphate levels, but serum levels of a phosphaturic hormone, fibroblast growth factor 23 (Fgf23), decreased in a dose-dependent manner. Subsequently, high-dose nicotinamide (40mM) was tested in Galnt3 knockout mice fed a high phosphate diet. The radiographic data pre- and post-treatment showed that nicotinamide did not reverse the calcification. However, the treatment retarded calcification growth after 4weeks, while in the untreated animals, calcifications increased in size. The therapy did not affect serum phosphate levels, but intact Fgf23 decreased in the treated mice. The treated mice also had increased calcium in the heart. In summary, nicotinamide did not alter serum phosphate levels, likely due to compensatory decrease in Fgf23 to counteract the phosphate lowering effect of nicotinamide. Although increased calcium accumulation in the heart is a concern, the therapy appears to slow down the progression of ectopic calcifications

An Unusual Combination of Neurological Manifestations and Sudden Vision Loss in a Child with Familial Hyperphosphatemic Tumoral Calcinosis

Hyperphosphatemia in the absence of renal failure is an unusual occurrence, particularly in children, but is a common primary feature of familial hyperphosphatemic tumor calcinosis. We report a child with hyperphosphatemia who presented with multiple episodes of neurologic dysfunction involving lower motor neuron facial nerve palsy along with sequential visual loss. He also had an episode of stroke. There was an extensive metastatic calcification of soft tissue and vasculature. Hyperphosphatemia with normal serum alkaline phosphatase, calcium, parathyroid hormone, and renal function was noted. He was managed with hemodialysis and sevelamer (3 months) without much success in reducing serum phosphate level, requiring continuous ambulatory peritoneal dialysis (3 years). Intact fibroblast growth factor 23 (FGF23) was undetectable, with C-terminal FGF23 fragments significantly elevated (2575 RU/ml, normal A (p.N162K) mutation in FGF23 exon 3, confirming the diagnoses of primary FGF23 deficiency, the first case to be reported from India

Dietary phosphate restriction normalizes biochemical and skeletal abnormalities in a murine model of tumoral calcinosis

Mutations in the GALNT3 gene cause tumoral calcinosis characterized by ectopic calcifications due to persistent hyperphosphatemia. We recently developed Galnt3 knockout mice in a mixed background, which had hyperphosphatemia with increased bone mineral density (BMD) and infertility in males. To test the effect of dietary phosphate intake on their phenotype, Galnt3 knockout mice were generated in the C57BL/6J strain and fed various phosphate diets: 0.1% (low), 0.3% (low normal), 0.6% (normal), and 1.65% (high). Sera were analyzed for calcium, phosphorus, alkaline phosphatase, creatinine, blood urine nitrogen, 1,25-dihydroxyvitamin D, osteocalcin, tartrate-resistant acid phosphatase 5b, and fibroblast growth factor 23 (Fgf23). Femurs were evaluated by dual-energy x-ray absorptiometry, dynamic histomorphometry, and/or microcomputed tomography. Galnt3 knockout mice in C57BL/6J had the same biochemical phenotype observed in our previous study: hyperphosphatemia, inappropriately normal 1,25-dihydroxyvitamin D level, decreased alkaline phosphatase activity, and low intact Fgf23 concentration but high Fgf23 fragments. Skeletal analyses of their femurs revealed significantly high BMD with increased cortical bone area and trabecular bone volume. On all four phosphate diets, Galnt3 knockout mice had consistently higher phosphorus levels and lower alkaline phosphatase and intact Fgf23 concentrations than littermate controls. The low-phosphate diet normalized serum phosphorus, alkaline phosphatase, and areal BMD but failed to correct male infertility in Galnt3 knockout mice. The high-phosphate diet did not increase serum phosphorus concentration in either mutant or control mice due to a compensatory increase in circulating intact Fgf23 levels. In conclusion, dietary phosphate restriction normalizes biochemical and skeletal phenotypes of Galnt3 knockout mice and, thus, can be an effective therapy for tumoral calcinosis.We thank Drew Brown and Chris Newman for their assistance with micro-CT scanning and analysis. This work was supported by Indiana University School of Medicine Biomedical Research Grant (to S.I.), Showalter Biomedical Trust Grant (to S.I.), and National Institutes of Health Grant R01AR042228(to M.J.E.). The preparation of this report was partially supported by a KL2 career development award (to S.I.) from the Indiana Clinical and Translational Sciences Institute funded in part by National Institutes of Health Grant RR025760. Disclosure Summary: M.J.E. receives royalties from and is a consultant for Kyowa Hakko Kirin Co. Ltd. All other authors state that they have no conflicts of interest

Interferon Gamma, but not Calcitriol Improves the Osteopetrotic Phenotypes in ADO2 Mice

ADO2 is a heritable osteosclerotic disorder that usually results from heterozygous missense dominant negative mutations in the chloride channel 7 gene (CLCN7). ADO2 is characterized by a wide range of features and severity, including multiple fractures, impaired vision due to secondary bony overgrowth and/or the lack of the optical canal enlargement with growth, and osteonecrosis/osteomyelitis. The disease is presently incurable, although anecdotal evidence suggests that calcitriol and interferon gamma-1b (IFN-G) may have some beneficial effects. To identify the role of these drugs for the treatment of ADO2, we utilized a knock-in (G213R mutation in Clcn7) ADO2 mouse model that resembles the human disease. Six-week-old ADO2 heterozygous mice were administered vehicle (PBS) or calcitriol or IFN-G 5 times per week for 8 weeks. We determined bone phenotypes using DXA and μCT, and analyzed serum biochemistry and bone resorption markers. ADO2 mice treated with all doses of IFN-G significantly (p<0.05) attenuated the increase of whole body aBMD and distal femur BV/TV gain in both male and female compared to the vehicle group. In contrast, mice treated with low and medium doses of calcitriol showed a trend of higher aBMD and BV/TV whereas high dose calcitriol significantly (p<0.05) increased bone mass compared to the vehicle group. The calcium and phosphorus levels did not differ between vehicle and IFN-G or calcitriol treated mice; however, we detected significantly (p<0.05) elevated levels of CTX/TRAP5b ratio in IFN-G treated mice. Our findings indicate that while IFN-G at all doses substantially improved the osteopetrotic phenotypes in ADO2 heterozygous mice, calcitriol treatment at any dose did not improve the phenotype and at high dose further increased bone mass. Thus, use of high dose calcitriol therapy in ADO2 patients merits serious reconsideration. Importantly, our data support the prospect of a clinical trial of IFN-G in ADO2 patients

Noncardiac genetic predisposition in sudden infant death syndrome.

PURPOSE: Sudden infant death syndrome (SIDS) is the commonest cause of sudden death of an infant; however, the genetic basis remains poorly understood. We aimed to identify noncardiac genes underpinning SIDS and determine their prevalence compared with ethnically matched controls. METHODS: Using exome sequencing we assessed the yield of ultrarare nonsynonymous variants (minor allele frequency [MAF] ≤0.00005, dominant model; MAF ≤0.01, recessive model) in 278 European SIDS cases (62% male; average age =2.7 ± 2 months) versus 973 European controls across 61 noncardiac SIDS-susceptibility genes. The variants were classified according to American College of Medical Genetics and Genomics criteria. Case-control, gene-collapsing analysis was performed in eight candidate biological pathways previously implicated in SIDS pathogenesis. RESULTS: Overall 43/278 SIDS cases harbored an ultrarare single-nucleotide variant compared with 114/973 controls (15.5 vs. 11.7%, p=0.10). Only 2/61 noncardiac genes were significantly overrepresented in cases compared with controls (ECE1, 3/278 [1%] vs. 1/973 [0.1%] p=0.036; SLC6A4, 2/278 [0.7%] vs. 1/973 [0.1%] p=0.049). There was no difference in yield of pathogenic or likely pathogenic variants between cases and controls (1/278 [0.36%] vs. 4/973 [0.41%]; p=1.0). Gene-collapsing analysis did not identify any specific biological pathways to be significantly associated with SIDS. CONCLUSIONS: A monogenic basis for SIDS amongst the previously implicated noncardiac genes and their encoded biological pathways is negligible

Safety and Tolerability of SRX246, a Vasopressin 1a Antagonist, in Irritable Huntington\u27s Disease Patients-A Randomized Phase 2 Clinical Trial.

SRX246 is a vasopressin (AVP) 1a receptor antagonist that crosses the blood-brain barrier. It reduced impulsive aggression, fear, depression and anxiety in animal models, blocked the actions of intranasal AVP on aggression/fear circuits in an experimental medicine fMRI study and demonstrated excellent safety in Phase 1 multiple-ascending dose clinical trials. The present study was a 3-arm, multicenter, randomized, placebo-controlled, double-blind, 12-week, dose escalation study of SRX246 in early symptomatic Huntington\u27s disease (HD) patients with irritability. Our goal was to determine whether SRX246 was safe and well tolerated in these HD patients given its potential use for the treatment of problematic neuropsychiatric symptoms. Participants were randomized to receive placebo or to escalate to 120 mg twice daily or 160 mg twice daily doses of SRX246. Assessments included standard safety tests, the Unified Huntington\u27s Disease Rating Scale (UHDRS), and exploratory measures of problem behaviors. The groups had comparable demographics, features of HD and baseline irritability. Eighty-two out of 106 subjects randomized completed the trial on their assigned dose of drug. One-sided exact-method confidence interval tests were used to reject the null hypothesis of inferior tolerability or safety for each dose group vs. placebo. Apathy and suicidality were not affected by SRX246. Most adverse events in the active arms were considered unlikely to be related to SRX246. The compound was safe and well tolerated in HD patients and can be moved forward as a candidate to treat irritability and aggression

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Intronic deletions in the SLC34A3 gene: a cautionary tale for mutation analysis of hereditary hypophosphatemic rickets with hypercalciuria

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare metabolic disorder, characterized by hypophosphatemia, variable degrees of rickets/osteomalacia, and hypercalciuria secondary to increased serum 1,25-dihydroxyvitamin D [1,25(OH)2D] levels. HHRH is caused by mutations in the SLC34A3 gene, which encodes sodium-phosphate co-transporter type IIc. A 6 ½-year-old female presented with a history of nephrolithiasis. Her metabolic evaluation revealed increased 24- hour urine calcium excretion with high serum calcium, low intact parathyroid hormone (PTH) levels, and elevated 1,25(OH)2D level. In addition, the patient had low to low-normal serum phosphorus with high urine phosphorus. The patient had normal stature; without rachitic or boney deformities or a history of fractures. Genetic analysis of SLC34A3 revealed the patient to be a compound heterozygote for a novel single base pair deletion in exon 12 (c.1304delG) and 30-base pair deletion in intron 6 (g.1440–1469del). The single-base pair mutation causes a frameshift, which results in premature stop codon. The intronic deletion is likely caused by misalignment of the 4-basepair homologous repeats and results in the truncation of an already small intron to 63 bp, which would impair proper RNA splicing of the intron. This is the fourth unique intronic deletion identified in patients with HHRH, suggesting the frequent occurrence of sequence misalignments in SLC34A3 and the importance of screening introns in patients with HHRH