Circulating MicroRNA as a Potential Biomarker for Skeletal Disease in Primary Hyperparathyroidism: A Case-control Study.

OBJECTIVE: The goal of this study was to characterize the microRNA (miRNA) expression signatures in patients with Primary hyperparathyroidism (PHPT) and identify miRNA biomarkers of bone homeostasis. BACKGROUND: PHPT is associated with increased bone turnover and decreased bone mass. miRNA are markers of bone remodeling. METHODS: We performed a prospective case-control study of postmenopausal females with PHPT and control subjects matched for race, age, and bone mineral density (BMD). We collected clinical and biochemical data, assessed BMD by dual-energy x-ray absorptiometry, and measured 27 serum miRNAs related to bone remodeling. We used linear regression to assess the correlation between miRNA levels, conventional biochemical markers, and BMD. RESULTS: A total of 135 subjects were evaluated, including 49 with PHPT (discovery group), 47 control patients without PHPT, and an independent validation cohort of 39 PHPT patients. Of 27 miRNAs evaluated, 9 (miR-335-5p, miR-130b-3p, miR-125b-5p, miR-23a-3p, miR-152-3p, miR-582-5p, miR-144-5p, miR-320a, and miR-19b-3p) were differentially expressed in PHPT compared with matched control subjects. All 9 differentially expressed miRNAs significantly correlated with levels of serum parathyroid hormone (PTH), and 8 of the 9 correlated with calcium levels. No differentially expressed miRNAs were consistently correlated with markers of BMD. Subjects with PHPT segregate from controls based on the signature of these 9 miRNAs on principle component analysis. CONCLUSIONS: These data suggest that PHPT is characterized by a unique miRNA signature that is distinct from postmenopausal and idiopathic osteoporosis. Levels of specific miRNAs significantly correlate with PTH, suggesting that bone remodeling in PHPT may be mediated in part by PTH-induced changes in miRNA.

Expanding the Phenotypic Spectrum of Kenny-Caffey Syndrome.

CONTEXT: Kenny-Caffey syndrome (KCS) is a rare hereditary disorder characterized by short stature, hypoparathyroidism, and electrolyte disturbances. KCS1 and KCS2 are caused by pathogenic variants in TBCE and FAM111A, respectively. Clinically the phenotypes are difficult to distinguish. OBJECTIVE: The objective was to determine and expand the phenotypic spectrum of KCS1 and KCS2 in order to anticipate complications that may arise in these disorders. METHODS: We clinically and genetically analyzed 10 KCS2 patients from 7 families. Because we found unusual phenotypes in our cohort, we performed a systematic review of genetically confirmed KCS cases using PubMed and Scopus. Evaluation by 3 researchers led to the inclusion of 26 papers for KCS1 and 16 for KCS2, totaling 205 patients. Data were extracted following the Cochrane guidelines and assessed by 2 independent researchers. RESULTS: Several patients in our KCS2 cohort presented with intellectual disability (3/10) and chronic kidney disease (6/10), which are not considered common findings in KCS2. Systematic review of all reported KCS cases showed that the phenotypes of KCS1 and KCS2 overlap for postnatal growth retardation (KCS1: 52/52, KCS2: 23/23), low parathyroid hormone levels (121/121, 16/20), electrolyte disturbances (139/139, 24/27), dental abnormalities (47/50, 15/16), ocular abnormalities (57/60, 22/23), and seizures/spasms (103/115, 13/16). Symptoms more prevalent in KCS1 included intellectual disability (74/80, 5/24), whereas in KCS2 bone cortical thickening (1/18, 16/20) and medullary stenosis (7/46, 27/28) were more common. CONCLUSION: Our case series established chronic kidney disease as a new feature of KCS2. In the literature, we found substantial overlap in the phenotypic spectra of KCS1 and KCS2, but identified intellectual disability and the abnormal bone phenotype as the most distinguishing features.

Early identification of a 12-bp tandem duplication in TNFRSF11A encoding receptor activator of nuclear factor-kappa B (RANK): Clinical characterization and response to bisphosphonate therapy.

INTRODUCTION: Ultra-rare mendelian osteolytic disorders caused by different length in-frame activating duplications within exon 1 of TNFRSF11A encoding receptor activator of nuclear factor-kappa B (RANK) comprise familial expansile osteolysis (FEO), expansile skeletal hyperphosphatasia (ESH), early-onset familial Paget's disease of bone (PDB2), juvenile Paget's disease 2 (JPD2), and panostotic expansile bone disease (PEBD). FEO typically presents with childhood-onset deafness followed by resorption of permanent dentition, and then appendicular bone pain, fractures, and deformities from progressive focal expansile osteolytic lesions emerging from a background of generalized high bone turnover. An 18-bp duplication in TNFRSF11A has been reported in all kindreds with FEO, whereas a 12-bp duplication was found in the young man with PEBD complicated by a massive jaw tumor. We report the clinical course and successful treatment with bisphosphonates of a girl with the 12-bp duplication yet a skeletal phenotype seemingly milder than PEBD. CASE PRESENTATION AND DISCUSSION: This 10-year-old girl presented for dental and orthodontic treatment and was found to have progressive external tooth root resorption. Speech delay was identified at age 18 months, and audiological evaluation showed both conductive and sensorineural hearing loss subsequently treated with a cochlear implant at age 3 years. Biochemical studies indicated increased bone turnover with elevated urinary N-telopeptide levels and serum alkaline phosphatase in the upper normal range. Low lumbar spine bone mineral density (BMD) was revealed by dual-energy X-ray absorptiometry, but whole-body Technetium-99 m bone scintigraphy was normal. Genetic testing identified the identical de novo 12-bp duplication within exon 1 of TNFRSF11A harbored by the young man with PEBD and massive jaw tumor. Bisphosphonate treatment, initiated with one dose of intravenous zoledronic acid that caused prolonged hypocalcemia, then comprised weekly oral alendronate that decreased bone turnover markers and normalized her BMD. CONCLUSION: Constitutive activation of RANK signaling should be considered a possible cause in any young person with rapid bone turnover, particularly in the context of early-onset deafness and/or root resorption of permanent teeth. Early diagnosis and anti-resorptive treatment, given judiciously to avoid sudden and prolonged hypocalcemia, may prevent further skeletal disease.

One half-century of advances in the evaluation and management of disorders of bone and mineral metabolism in children and adolescents.

The past 50 years of research in pediatric bone and mineral metabolism have led to remarkable progress in the identification and characterization of disorders that affect the developing skeleton. Progress has been facilitated through advances in both technology and biology and this paper provides a brief description of some but not all of the key findings, including identification of the calcium sensing receptor and the polypeptides parathyroid hormone and parathyroid hormone-related protein as well as their shared receptor and signal generating pathways; the elucidation of vitamin D metabolism and actions; discovery of fibroblast growth factor 23 (FGF23), the sodium-phosphate co-transporters and the other components that regulate phosphate metabolism. Moreover, the past half-century of research has led to the delineation of the molecular bases for genetic forms of hypoparathyroidism, pseudohypoparathyroidism, and primary hyperparathyroidism as well as the determination of the genetic causes of osteogenesis imperfecta, osteopetrosis, hypophosphatasia, and other disorders of mineral/bone homeostasis. During the next decade we expect that many of these fundamental discoveries will lead to the development of innovative treatments that will improve the lives of children with these disorders.

Hispanic adults with type 2 diabetes mellitus using lipid-lowering agents have better periodontal health than non-users.

Background: Recent studies suggest that lipid-lowering agents (LLA) may reduce chronic periodontitis, but it is unknown whether this benefit extends to people with type 2 diabetes (T2D). Objective: We assessed the association between LLA use and periodontitis in Hispanic adults with T2D. Design: This was a cross-sectional observational study. Methods: We assessed the association of LLA use and periodontal parameters in 253 Puerto Ricans 40-65 years with T2D who participated in the Lipid-Lowering agents use in Periodontitis and Diabetes Study study. Participants were classified as (a) none- or <1 year, (b) 1-4 years, or (c) >4 years. The primary outcome consists of a tertile percent of sites with probing pocket depth (PPD) ⩾ 4 mm and the secondary outcome includes tertiles of percent sites with clinical attachment loss (CAL) ⩾ 4 mm. Multinomial logistic regression models adjusted for age, gender, smoking status, education, waist circumference, glycosylated hemoglobin A1C (HbA1c), bleeding on probing, examiner, and anti-inflammatory agents were used to estimate the association. Results: LLA (92.5%, statins) was used by 52% of participants. LLA use 1-4 years was associated with lower odds of PPD ⩾ 4 mm (OR: 0.22, p = 0.005; high versus low tertile) or lower odds of CAL ⩾ 4 mm (OR: 0.33, p = 0.02, middle versus low tertile), compared to those with LLA minimal or no use. This association was lost for participants who used LLA for >4 years. LLA users for >4 years with periodontal disease had elevated HbA1c (OR: 1.36, p = 0.05). Conclusion: The use of LLA for 1-4 years was associated with lower values of periodontal parameters versus minimal LLA use. This association was not present among people using LLA > 4 years users, but these participants had poorer glycemic control compared to other participants. In this cross-sectional study, the finding that LLA use 1- 4 years is associated with lower values of periodontal parameters of severity in T2D individuals may help clarify some of the controversies regarding the benefit of these medications in this population.

Lipid-lowering agents and lower values of periodontal parameters in individuals with type 2 diabetes • Lipid-lowering agents (LLA), such as statins, are reported to reduce chronic periodontitis, making individuals with diabetes ideal candidates for this treatment due to their high prevalence of oral disease.• The association between LLA use and periodontitis was assessed among Hispanic adults with type 2 diabetes (T2D).• Short-term LLA use (but not long-term use) was associated with lower values of periodontal parameters in individuals with T2D.• For long-term LLA use, high glycemic level was associated with high values of periodontitis.• Thus, under the study design limitations, the finding may provide clinical implications and may help clarify some of the controversies regarding the benefits of LLA use in humans.• Furthermore, the higher glycemic levels for periodontal patients with long-term LLA use points to the need to monitor these patients carefully.

Etiology and Pathophysiology of Hypoparathyroidism: A Narrative Review.

The approach utilized a systematic review of the medical literature executed with specifically designed criteria that focused on the etiologies and pathogenesis of hypoparathyroidism. Enhanced attention by endocrine surgeons to new knowledge about parathyroid gland viability are reviewed along with the role of intraoperative parathyroid hormone (ioPTH) monitoring during and after neck surgery. Nonsurgical etiologies account for a significant proportion of cases of hypoparathyroidism (~25%), and among them, genetic etiologies are key. Given the pervasive nature of PTH deficiency across multiple organ systems, a detailed review of the skeletal, renal, neuromuscular, and ocular complications is provided. The burden of illness on affected patients and their caregivers contributes to reduced quality of life and social costs for this chronic endocrinopathy. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Novel PTH Gene Mutations Causing Isolated Hypoparathyroidism.

CONTEXT: Parathyroid hormone (PTH) gene mutations represent a rare cause of familial isolated hypoparathyroidism (FIH). These defects can cause hypoparathyroidism with increased or decreased serum levels of PTH through 1) impaired PTH synthesis; 2) induction of parathyroid cell apoptosis; or 3) secretion of bioinactive PTH molecules. Eight pathogenic mutations of this gene have been described previously. OBJECTIVE: Through describing 2 novel mutations of the PTH gene, we aim to extend the molecular basis for FIH and further refine the proposed mechanisms by which PTH mutations cause hypoparathyroidism. METHODS: Proband case reports were compiled with extended family analysis. The probands in both kindreds presented before age 10 days with hypocalcemia and elevated phosphate levels. Proband A had low PTH levels, whereas these levels were elevated in Proband B. Proband B was initially diagnosed with pseudohypoparathyroidism. Methylation analysis was performed of CpG dinucleotides within 3 GNAS differentially methylated regions; whole-genome sequencing; and PTH infusion with analysis of nephrogenous 3',5'-cyclic adenosine 5'-monophosphate. RESULTS: Proband A had a novel heterozygous sequence change in exon 2 of the PTH gene, c.46_47delinsAA (p.Ala16Lys), and proband B had a novel homozygous nucleotide transition in PTH exon 3 (c.128G > A; p.G43E) that led to replacement of glycine by glutamic acid at position 12 of PTH 1-84. PTH 1-34 infusion demonstrated that renal responsiveness to PTH was intact and not antagonized by circulating bioinactive PTH. CONCLUSION: PTH gene mutations are uncommon causes of hypoparathyroidism, but can be misdiagnosed as disorders of gland development or receptor function if PTH levels are decreased or elevated, respectively. Genetic testing should be considered early in the diagnostic approach to these presentations.

Parenteral iron therapy and phosphorus homeostasis: A review.

Phosphorus has an essential role in cellular and extracellular metabolism; maintenance of normal phosphorus homeostasis is critical. Phosphorus homeostasis can be affected by diet and certain medications; some intravenous iron formulations can induce renal phosphate excretion and hypophosphatemia, likely through increasing serum concentrations of intact fibroblast growth factor 23. Case studies provide insights into two types of hypophosphatemia: acute symptomatic and chronic hypophosphatemia, while considering the role of pre-existing conditions and comorbidities, medications, and intravenous iron. This review examines phosphorus homeostasis and hypophosphatemia, with emphasis on effects of iron deficiency and iron replacement using intravenous iron formulations.

PRKACB variants in skeletal disease or adrenocortical hyperplasia: effects on protein kinase A.

Genetic variants in components of the protein kinase A (PKA) enzyme have been associated with various defects and neoplasms in the context of Carney complex (CNC) and in isolated cases, such as in primary pigmented nodular adrenocortical disease (PPNAD), cortisol-producing adrenal adenomas (CPAs), and various cancers. PRKAR1A mutations have been found in subjects with impaired cAMP-dependent signaling and skeletal defects; bone tumors also develop in both humans and mice with PKA abnormalities. We studied the PRKACB gene in 148 subjects with PPNAD and related disorders, who did not have other PKA-related defects and identified two subjects with possibly pathogenic PRKACB gene variants and unusual bone and endocrine phenotypes. The first presented with bone and other abnormalities and carried a de novo c.858_860GAA (p.K286del) variant. The second subject carried the c.899C>T (p.T300M or p.T347M in another isoform) variant and had a PPNAD-like phenotype. Both variants are highly conserved in the PRKACB gene. In functional studies, the p.K286del variant affected PRKACB protein stability and led to increased PKA signaling. The p.T300M variant did not affect protein stability or response to cAMP and its pathogenicity remains uncertain. We conclude that PRKACB germline variants are uncommon but may be associated with phenotypes that resemble those of other PKA-related defects. However, detailed investigation of each variant is needed as PRKACB appears to be only rarely affected in these conditions, and variants such as p.T300M maybe proven to be clinically insignificant, whereas others (such as p.K286del) are clearly pathogenic and may be responsible for a novel syndrome, associated with endocrine and skeletal abnormalities.

Short Stature is Progressive in Patients with Heterozygous NPR2 Mutations.

BACKGROUND: NPR2 encodes atrial natriuretic peptide receptor B (ANPRB), a regulator of skeletal growth. Biallelic loss-of-function mutations in NPR2 result in acromesomelic dysplasia Maroteaux type (AMDM; OMIM 602875), while heterozygous mutations may account for 2% to 6% of idiopathic short stature (ISS). OBJECTIVE: Describe the physical proportions and growth characteristics of an extended family with novel NPR2 mutations including members with AMDM, ISS, or normal stature. DESIGN AND PARTICIPANTS: We performed whole exome sequencing in 2 healthy parents and 2 children with AMDM. Detailed genotyping and phenotyping were performed on members of a multigenerational family in an academic medical center. We expressed mutant proteins in mammalian cells and characterized expression and function. RESULTS: The sisters with AMDM were compound heterozygotes for missense mutations in the NPR2 gene, a novel p.P93S (maternal) and the previously reported p.R989L (paternal). Both mutant ANPRB proteins were normally expressed in HEK293T cells and exhibited dominant negative effects on wild-type ANPRB catalytic activity. Heterozygous relatives had proportionate short stature (height z-scores -2.06 ± 0.97, median ± SD) compared with their wild-type siblings (-1.37 ± 0.59). Height z-scores progressively and significantly decreased as NPR2-heterozygous children matured, while remaining constant in their wild-type siblings. CONCLUSIONS: Biallelic NPR2 mutations cause severe skeletal dysplasia (AMDM), whereas heterozygous mutations lead to a subtler phenotype characterized by progressive short stature with by increasing loss of height potential with age.

Single Gland, Ectopic Location: Adenomas are Common Causes of Primary Hyperparathyroidism in Children and Adolescents.

BACKGROUND: Primary hyperparathyroidism (PHPT) in children and adolescents is uncommon. Data-driven guidelines for management in pediatric patients are limited. METHODS: We performed a retrospective cohort analysis of all patients (1997-2017) with PHPT ≤ 21 years of age who underwent parathyroidectomy at three institutions. Clinical and demographic variables were analyzed. Primary operative outcome was cure (normocalcemia > 6 months after surgery); secondary outcome was operative success (intraoperative parathyroid hormone decrease of ≥ 50%). RESULTS: We identified 86 patients with a median age of 17 years (IQR: 14, 19); 64% (n = 55) were female. The mean preoperative serum calcium was 11.7 mg/dL, median parathyroid hormone (PTH) was 110 pg/mL, and median urine calcium was 4.1 mg/kg/24 h. Preoperatively, sestamibi scan localized in 41/71 patients (58%); neck ultrasound localized in 19/44 (43%). The most common pathology at surgery was a single ectopic parathyroid adenoma in 71% (n = 61). A high incidence of ectopic adenomas (25%, n = 22) was observed, most commonly intrathymic (n = 13), followed by tracheoesophageal groove (n = 5), carotid sheath (n = 2), and intrathyroidal (n = 2). Of 56 patients with retrievable data > 6 months postoperatively, cure was achieved in 55 of 56 patients (98%). One patient who presented to us with parathyromatosis require subsequent reoperation. CONCLUSION: In this multi-institutional series of PHPT in children and adolescents, the majority were sporadic PHPT and were due to a single adenoma. We observed a high incidence of ectopic parathyroid adenomas, most commonly intrathymic. Given the high risk for ectopic adenoma in pediatric patients, parathyroid surgery in children and adolescents should be performed by experienced surgeons.

Multidisciplinary guidelines for initial evaluation of complicated lymphatic anomalies-expert opinion consensus.

OBJECTIVE: Complicated lymphatic anomalies (CLAs) are chronic, progressive, and debilitating conditions that share clinical features, yet key elements for optimal evaluation and management have not been established. We aimed to formulate expert opinion consensus-based guidelines for comprehensive evaluation of CLAs. STUDY DESIGN: Patient support groups dedicated to CLAs organized an international conference for vascular anomaly experts from 16 specialties to address the objective. Participants received a set of questions before the meeting and reviewed the literature. Data extracted from international lymphatic anomaly registries were presented and the group separated for panel discussions during the conference. The recommendations achieving consensus within the panel were presented to the entire audience. Open debate occurred until majority approval was achieved. RESULTS: The expert group was composed of 52 physicians who defined the clinical elements required to evaluate and diagnose a CLA. The radiology panel established the preferred anatomical and functional imaging methods for diagnosis and the elements required to be described during interpretation. Two medical panels compiled the metabolic and hematologic tests at diagnosis and also recommended functional studies. The surgical group recommended precautions for biopsy and the pathology panel provided biopsy specimen processing guidelines. CONCLUSIONS: Patients with CLAs require a comprehensive and targeted diagnostic plan for appropriate management, prevention of complications, and conservation of resources. As this population is managed by diverse medical and surgical specialties, we offer an expert multidisciplinary consensus-based opinion on the current literature and on data extracted from international lymphatic anomaly registries.

ARAF recurrent mutation causes central conducting lymphatic anomaly treatable with a MEK inhibitor.

The treatment of lymphatic anomaly, a rare devastating disease spectrum of mostly unknown etiologies, depends on the patient manifestations1. Identifying the causal genes will allow for developing affordable therapies in keeping with precision medicine implementation2. Here we identified a recurrent gain-of-function ARAF mutation (c.640T>C:p.S214P) in a 12-year-old boy with advanced anomalous lymphatic disease unresponsive to conventional sirolimus therapy and in another, unrelated, adult patient. The mutation led to loss of a conserved phosphorylation site. Cells transduced with ARAF-S214P showed elevated ERK1/2 activity, enhanced lymphangiogenic capacity, and disassembly of actin skeleton and VE-cadherin junctions, which were rescued using the MEK inhibitor trametinib. The functional relevance of the mutation was also validated by recreating a lymphatic phenotype in a zebrafish model, with rescue of the anomalous phenotype using a MEK inhibitor. Subsequent therapy of the lead proband with a MEK inhibitor led to dramatic clinical improvement, with remodeling of the patient's lymphatic system with resolution of the lymphatic edema, marked improvement in his pulmonary function tests, cessation of supplemental oxygen requirements and near normalization of daily activities. Our results provide a representative demonstration of how knowledge of genetic classification and mechanistic understanding guides biologically based medical treatments, which in our instance was life-saving.

Inhibition of Tissue-Nonspecific Alkaline Phosphatase Attenuates Ectopic Mineralization in the Abcc6-/- Mouse Model of PXE but Not in the Enpp1 Mutant Mouse Models of GACI.

Pseudoxanthoma elasticum (PXE), a prototype of heritable ectopic mineralization disorders, is caused by mutations in the ABCC6 gene encoding a putative efflux transporter ABCC6. It was recently shown that the absence of ABCC6-mediated adenosine triphosphate release from the liver and, consequently, reduced inorganic pyrophosphate levels underlie the pathogenesis of PXE. Given that tissue-nonspecific alkaline phosphatase (TNAP), encoded by ALPL, is the enzyme responsible for degrading inorganic pyrophosphate, we hypothesized that reducing TNAP levels either by genetic or pharmacological means would lead to amelioration of the ectopic mineralization phenotype in the Abcc6-/- mouse model of PXE. Thus, we bred Abcc6-/- mice to heterozygous Alpl+/- mice that display approximately 50% plasma TNAP activity. The Abcc6-/-Alpl+/- double-mutant mice showed 52% reduction of mineralization in the muzzle skin compared with the Abcc6-/-Alpl+/+ mice. Subsequently, oral administration of SBI-425, a small molecule inhibitor of TNAP, resulted in 61% reduction of plasma TNAP activity and 58% reduction of mineralization in the muzzle skin of Abcc6-/- mice. By contrast, SBI-425 treatment of Enpp1 mutant mice, another model of ectopic mineralization associated with reduced inorganic pyrophosphate, failed to reduce muzzle skin mineralization. These results suggest that inhibition of TNAP might provide a promising treatment strategy for PXE, a currently intractable disease.

Gestational Gigantomastia Complicated by PTHrP-Mediated Hypercalcemia.

Context: Gestational gigantomastia is an uncommon condition characterized by abnormal and excessive growth of breast tissue during an otherwise uncomplicated pregnancy. Gestational gigantomastia may be accompanied by hypercalcemia, which in some cases has been associated with elevated serum levels of PTHrP. The source of the PTHrP in these cases has been suggested to be the enlarged breasts. Objective: To describe the rapid resolution of hypercalcemia and normalization of serum PTHrP after elective termination of pregnancy, indicating that the placenta was the source of the PTHrP. Design: A retrospective analysis of clinical and biochemical data over a 2-year interval and review of literature. Setting: An academic medical center. Patient: A 33-year-old G8P4 female who presented at week 8 of pregnancy with gestational gigantomastia and subsequently developed marked hypercalcemia at week 13. Serum levels of PTH were suppressed but circulating PTHrP was elevated. There was no history of hypercalcemia or significant breast growth during previous pregnancies. Intervention: Hypercalcemia was poorly responsive to IV saline, prednisone, calcitonin, and cinacalcet. She requested termination of pregnancy at week 20. Results: Serum levels of calcium, PTH, and PTHrP normalized within 48 hours of termination of pregnancy. Conclusion: The rapid resolution of hypercalcemia after termination of pregnancy, despite persistent gigantomastia, provides evidence for a pathologic role of the placenta in the excess production of PTHrP, possibly through an as yet uncharacterized placenta-breast hormonal axis.

Pathogenic variant in EPHB4 results in central conducting lymphatic anomaly.

Central conducting lymphatic anomaly (CCLA) is one of the complex lymphatic anomalies characterized by dilated lymphatic channels, lymphatic channel dysmotility and distal obstruction affecting lymphatic drainage. We performed whole exome sequencing (WES) of DNA from a four-generation pedigree and examined the consequences of the variant by transfection of mammalian cells and morpholino and rescue studies in zebrafish. WES revealed a heterozygous mutation in EPHB4 (RefSeq NM_004444.4; c.2334 + 1G>C) and RNA-Seq demonstrated that the EPHB4 mutation destroys the normal donor site, which leads to the use of a cryptic splice donor that results in retention of the intervening 12-bp intron sequence. Transient co-expression of the wild-type and mutant EPHB4 proteins showed reduced phosphorylation of tyrosine, consistent with a loss-of-function effect. Zebrafish ephb4a morpholino resulted in vessel misbranching and deformities in the lymphatic vessel development, indicative of possible differentiation defects in lymphatic vessels, mimicking the lymphatic presentations of the patients. Immunoblot analysis using zebrafish lysates demonstrated over-activation of mTORC1 as a consequence of reduced EPHB4 signaling. Strikingly, drugs that inhibit mTOR signaling or RAS-MAPK signaling effectively rescued the misbranching phenotype in a comparable manner. Moreover, knock-in of EPHB4 mutation in HEK293T cells also induced mTORC1 activity. Our data demonstrate the pathogenicity of the identified EPHB4 mutation as a novel cause of CCLA and suggesting that ERK inhibitors may have therapeutic benefits in such patients with complex lymphatic anomalies.

Proteasome inhibitor bortezomib is a novel therapeutic agent for focal radiation-induced osteoporosis.

Bone atrophy and its related fragility fractures are frequent, late side effects of radiotherapy in cancer survivors and have a detrimental impact on their quality of life. In another study, we showed that parathyroid hormone 1-34 and anti-sclerostin antibody attenuates radiation-induced bone damage by accelerating DNA repair in osteoblasts. DNA damage responses are partially regulated by the ubiquitin proteasome pathway. In the current study, we examined whether proteasome inhibitors have similar bone-protective effects against radiation damage. MG132 treatment greatly reduced radiation-induced apoptosis in cultured osteoblastic cells. This survival effect was owing to accelerated DNA repair as revealed by γH2AX foci and comet assays and to the up-regulation of Ku70 and DNA-dependent protein kinase, catalytic subunit, essential DNA repair proteins in the nonhomologous end-joining pathway. Administration of bortezomib (Bzb) reversed the loss of trabecular bone structure and strength in mice at 4 wk after focal radiation. Histomorphometry revealed that Bzb significantly increased the number of osteoblasts and activity in the irradiated area and suppressed the number and activity of osteoclasts, regardless of irradiation. Two weeks of Bzb treatment accelerated DNA repair in bone-lining osteoblasts and thus promoted their survival. Meanwhile, it also inhibited bone marrow adiposity. Taken together, we demonstrate a novel role of proteasome inhibitors in treating radiation-induced osteoporosis.-Chandra, A., Wang, L., Young, T., Zhong, L., Tseng, W.-J., Levine, M. A., Cengel, K., Liu, X. S., Zhang, Y., Pignolo, R. J., Qin, L. Proteasome inhibitor bortezomib is a novel therapeutic agent for focal radiation-induced osteoporosis.

Diagnosis and Management of Osteopetrosis: Consensus Guidelines From the Osteopetrosis Working Group.

Background: Osteopetrosis encompasses a group of rare metabolic bone diseases characterized by impaired osteoclast activity or development, resulting in high bone mineral density. Existing guidelines focus on treatment of the severe infantile forms with hematopoietic cell transplantation (HCT) but do not address the management of patients with less severe forms for whom HCT is not the standard of care. Therefore, our objective was to develop expert consensus guidelines for the management of these patients. Methods: A modified Delphi method was used to build consensus among participants of the Osteopetrosis Working Group, with responses to an anonymous online survey used to identify areas of agreement and conflict and develop a follow-up survey. The strength of recommendations and quality of evidence was graded using the Grading of Recommendations Assessment, Development and Evaluation system. Results: Consensus was found in the areas of diagnosis, monitoring, and treatment. We recommend relying on characteristic radiographic findings to make the diagnosis and found that genetic testing adds important information by identifying mutations associated with unique disease complications. We recommend ongoing monitoring for changes in mineral metabolism and other complications, including cranial nerve impingement, anemia, leukopenia, and dental disease. We suggest that calcitriol should not be used in high doses and instead recommend symptom-based supportive therapy for disease complications because noninfantile osteopetrosis has no effective treatment. Conclusions: Scarcity of published studies on osteopetrosis reduce the ability to develop evidence-based guidelines for the management of these patients. Expert opinion-based guidelines for this rare condition are nevertheless important to enable improved care.

Digenic Inheritance of PROKR2 and WDR11 Mutations in Pituitary Stalk Interruption Syndrome.

Context: Pituitary stalk interruption syndrome (PSIS, ORPHA95496) is a congenital defect of the pituitary gland characterized by the triad of a very thin/interrupted pituitary stalk, an ectopic (or absent) posterior pituitary gland, and hypoplasia or aplasia of the anterior pituitary gland. Complex genetic patterns of inheritance of this disorder are increasingly recognized. Objective: The objective of this study was to identify a genetic cause of PSIS in an affected child. Methods: Whole exome sequencing (WES) was performed by using standard techniques, with prioritized genetic variants confirmed via Sanger sequencing. To investigate the effects of one candidate variant on mutant WDR11 function, Western blotting and coimmunofluorescence were used to assess binding capacity, and leptomycin B exposure along with immunofluorescence was used to assess nuclear localization. Results: We describe a child who presented in infancy with combined pituitary hormone deficiencies and whose brain imaging demonstrated a small anterior pituitary, ectopic posterior pituitary, and a thin, interrupted stalk. WES demonstrated heterozygous missense mutations in two genes required for pituitary development, a known loss-of-function mutation in PROKR2 (c.253C>T;p.R85C) inherited from an unaffected mother, and a WDR11 (c.1306A>G;p.I436V) mutation inherited from an unaffected father. Mutant WDR11 loses its capacity to bind to its functional partner, EMX1, and to localize to the nucleus. Conclusions: WES in a child with PSIS and his unaffected family implicates a digenic mechanism of inheritance. In cases of hypopituitarism in which there is incomplete segregation of a monogenic genotype with the phenotype, the possibility that a second genetic locus is involved should be considered.