Developmental Dysplasia of the Hip: Linkage Mapping and Whole Exome Sequencing Identify a Shared Variant in CX3CR1 in All Affected Members of a Large Multigeneration Family

Developmental dysplasia of the hip (DDH) is a debilitating condition characterized by incomplete formation of the acetabulum leading to dislocation of the femur, suboptimal joint function, and accelerated wear of the articular cartilage resulting in arthritis. DDH affects 1 in 1000 newborns in the United States; there are well‐defined “pockets” of high prevalence in Japan, and in Italy and other Mediterranean countries. Although reasonably accurate for detecting gross forms of hip dysplasia, existing techniques fail to find milder forms of dysplasia. Undetected hip dysplasia is the leading cause of osteoarthritis of the hip in young individuals, causing over 40% of cases in this age group. A sensitive and specific test for DDH has remained a desirable yet elusive goal in orthopedics for a long time. A 72‐member, four‐generation affected family has been recruited, and DNA from its members retrieved. Genomewide linkage analysis revealed a 2.61‐Mb candidate region (38.7–41.31 Mb from the p term of chromosome 3) co‐inherited by all affected members with a maximum logarithm (base 10) of odds (LOD) score of 3.31. Whole exome sequencing and analysis of this candidate region in four severely affected family members revealed one shared variant, rs3732378, that causes a threonine (polar) to methionine (non‐polar) alteration at position 280 in the transmembrane domain of CX3CR1. This mutation is predicted to have a deleterious effect on its encoded protein, which functions as a receptor for the ligand fractalkine. By Sanger sequencing this variant was found to be present in the DNA of all affected individuals and obligate heterozygotes. CX3CR1 mediates cellular adhesive and migratory functions and is known to be expressed in mesenchymal stem cells destined to become chondrocytes. A genetic risk factor that might be among the etiologic factors for the family in this study has been identified, along with other possible aggravating mutations shared by four severely affected family members. These findings might illuminate the molecular pathways affecting chondrocyte maturation and bone formation. © 2013 American Society for Bone and Mineral Research.     

Loss of heterozygosity on chromosomes 10q, 9p, 17p and 13q in Malays with malignant glioma

Abstract

Recent advances in neuro-oncology have revealed different pathways of molecular oncogenesis in malignant gliomas including loss of heterozygosity on chromosomal regions harboring tumor suppressor genes. In the present study, we performed polymerase chain reaction–loss of heterozygosity (PCR-LOH) analysis using microsatellite markers to identify loss of heterozygosity on chromosomes 10q, 9p, 17p and 13q in the Malays with malignant gliomas. Of 12 cases with allelic losses, seven (58.3%) cases showed LOH on chromosome 10q, three (25.0%) cases showed LOH on chromosome 9p, four (33.3%) cases showed LOH on chromosome 17p and two (16.7%) cases showed LOH on chromosome 13q. The cases include five (41.7%) cases of glioblastoma multiforme, three (25.0%) cases of anaplastic astrocytoma, three (25.0%) cases of anaplastic oligodendroglioma and one (8.3%) case of anaplastic ependymoma. Four cases showed loss of heterozygosity on more than one locus. Our findings showed that loss of heterozygosity on specific chromosomal regions contributes to the molecular pathway of glioma progression in Malay population. In addition, these data provide useful evidence of molecular genetic alterations of malignant glioma in South East Asian patients, particularly in the East Coast of Malaysia.     

Mortality and Causes of Death in Patients With Osteogenesis Imperfecta: A Register‐Based Nationwide Cohort Study

Osteogenesis imperfecta (OI) is a hereditary connective tissue disease that causes frequent fractures. Little is known about causes of death and length of survival in OI. The objective of this work was to calculate the risk and cause of death, and the median survival time in patients with OI. This study was a Danish nationwide, population‐based and register‐based cohort study. We used National Patient Register data from 1977 until 2013 with complete long‐term follow‐up. Participants comprised all patients registered with the diagnosis of OI from 1977 until 2013, and a reference population matched five to one to the OI cohort. We calculated hazard ratios for all‐cause mortality and subhazard ratios for cause‐specific mortality in a comparison of the OI cohort and the reference population. We also calculated all‐cause mortality hazard ratios for males, females, and age groups (0 to 17.99 years, 18.00 to 34.99 years, 35.00 to 54.99 years, 55.00 to 74.99 years, and >75 years). We identified 687 cases of OI (379 women) and included 3435 reference persons (1895 women). A total of 112 patients with OI and 257 persons in the reference population died during the observation period. The all‐cause mortality hazard ratio between the OI cohort and the reference population was 2.90. The median survival time for males with OI was 72.4 years, compared to 81.9 in the reference population. The median survival time for females with OI was 77.4 years, compared to 84.5 years in the reference population. Patients with OI had a higher risk of death from respiratory diseases, gastrointestinal diseases, and trauma. We were limited by the lack of clinical information about phenotype and genotype of the included patients. Patients with OI had a higher mortality rate throughout their life compared to the general population. © 2016 American Society for Bone and Mineral Research.     

Romosozumab Enhances Vertebral Bone Structure in Women With Low Bone Density

Romosozumab monoclonal antibody treatment works by binding sclerostin and causing rapid stimulation of bone formation while decreasing bone resorption. The location and local magnitude of vertebral bone accrual by romosozumab and how it compares to teriparatide remains to be investigated. Here we analyzed the data from a study collecting lumbar computed tomography (CT) spine scans at enrollment and 12 months post-treatment with romosozumab (210 mg sc monthly, n = 17), open-label daily teriparatide (20 μg sc, n = 19), or placebo (sc monthly, n = 20). For each of the 56 women, cortical thickness (Ct.Th), endocortical thickness (Ec.Th), cortical bone mineral density (Ct.bone mineral density (BMD)), cancellous BMD (Cn.BMD), and cortical mass surface density (CMSD) were measured across the first lumbar vertebral surface. In addition, color maps of the changes in the lumbar vertebrae structure were statistically analyzed and then visualized on the bone surface. At 12 months, romosozumab improved all parameters significantly over placebo and resulted in a mean vertebral Ct.Th increase of 10.3% versus 4.3% for teriparatide, an Ec.Th increase of 137.6% versus 47.5% for teriparatide, a Ct.BMD increase of 2.1% versus a −0.1% decrease for teriparatide, and a CMSD increase of 12.4% versus 3.8% for teriparatide. For all these measurements, the differences between romosozumab and teriparatide were statistically significant (p < 0.05). There was no significant difference between the romosozumab-associated Cn.BMD gains of 22.2% versus 18.1% for teriparatide, but both were significantly greater compared with the change in the placebo group (−4.6%, p < 0.05). Cortical maps showed the topographical locations of the increase in bone in fracture-prone areas of the vertebral shell, walls, and endplates. This study confirms widespread vertebral bone accrual with romosozumab or teriparatide treatment and provides new insights into how the rapid prevention of vertebral fractures is achieved in women with osteoporosis using these anabolic agents. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Propranolol Promotes Bone Formation and Limits Resorption Through Novel Mechanisms During Anabolic Parathyroid Hormone Treatment in Female C57BL/6J Mice

Although the nonselective β-blocker, propranolol, improves bone density with parathyroid hormone (PTH) treatment in mice, the mechanism of this effect is unclear. To address this, we used a combination of in vitro and in vivo approaches to address how propranolol influences bone remodeling in the context of PTH treatment. In female C57BL/6J mice, intermittent PTH and propranolol administration had complementary effects in the trabecular bone of the distal femur and fifth lumbar vertebra (L₅), with combination treatment achieving microarchitectural parameters beyond that of PTH alone. Combined treatment improved the serum bone formation marker, procollagen type 1 N propeptide (P1NP), but did not impact other histomorphometric parameters relating to osteoblast function at the L₅. In vitro, propranolol amplified the acute, PTH-induced, intracellular calcium signal in osteoblast-like cells. The most striking finding, however, was suppression of PTH-induced bone resorption. Despite this, PTH-induced receptor activator of nuclear factor κ-B ligand (RANKL) mRNA and protein levels were unaltered by propranolol, which led us to hypothesize that propranolol could act directly on osteoclasts. Using in situ methods, we found Adrb2 expression in osteoclasts in vivo, suggesting β-blockers may directly impact osteoclasts. Consistent with this, we found propranolol directly suppresses osteoclast differentiation in vitro. Taken together, this work suggests a strong anti-osteoclastic effect of nonselective β-blockers in vivo, indicating that combining propranolol with PTH could be beneficial to patients with extremely low bone density. © 2022 American Society for Bone and Mineral Research (ASBMR).     

Comparison of Fracture Prediction Tools in Individuals Without and With Early Chronic Kidney Disease: A Population-Based Analysis of CARTaGENE

Whether fracture prediction tools developed for the management of osteoporosis can be used in chronic kidney disease (CKD) is poorly known. We aimed to compare the performance of fracture prediction tools in non-CKD and CKD. We analyzed CARTaGENE, a population-based survey of 40-year-old to 69-year-old individuals recruited between 2009 and 2010. Renal function was assessed using baseline creatinine and categorized according to Kidney Disease Improving Global Outcomes (KDIGO) guidelines (non-CKD, stage 2, stage 3). Individuals without creatinine measurements or with advanced CKD (stage 4 or 5; prevalence <0.25%) were excluded. Predicted 5-year fracture probabilities (using Fracture Risk Assessment Tool [FRAX], QFracture, and Garvan) were computed at baseline. Fracture incidence (major fracture [MOF] or any fracture) was evaluated in administrative databases from recruitment to March 2016. Discrimination (hazard ratios [HRs] per standard deviation [SD] increase in Cox models; c-statistics) and calibration (standardized incidence ratios [SIRs] before and after recalibration) were assessed in each CKD strata. We included 19,393 individuals (9522 non-CKD; 9114 stage 2; 757 stage 3). A total of 830 patients had any fracture during follow-up, including 352 MOF. FRAX (HR = 1.89 [1.63–2.20] non-CKD; 1.64 [1.41–1.91] stage 2; 1.76 [1.10–2.82] stage 3) and QFracture (HR = 1.90 [1.62–2.22] non-CKD; 1.57 [1.35–1.82] stage 2; 1.86 [1.19–2.91] stage 3) discriminated MOF similarly in non-CKD and CKD. In contrast, the discrimination of Garvan for any fracture tended to be lower in CKD stage 3 compared to non-CKD and CKD stage 2 (HR = 1.36 [1.22–1.52] non-CKD; 1.34 [1.20–1.50] stage 2; 1.11 [0.79–1.55] stage 3). Before recalibration, FRAX globally overestimated fracture risk while QFracture and Garvan globally underestimated fracture risk. After recalibration, FRAX and QFracture were adequately calibrated for MOF in all CKD strata whereas Garvan tended to underestimate any fracture risk in CKD stage 3 (SIR = 1.31 [0.95–1.81]). In conclusion, the discrimination and calibration of FRAX and QFracture is similar in non-CKD and CKD. Garvan may have a lower discrimination in CKD stage 3 and underestimate fracture risk in these patients. © 2020 American Society for Bone and Mineral Research.     

Effects of Odanacatib on Bone Structure and Quality in Postmenopausal Women With Osteoporosis: 5-Year Data From the Phase 3 Long-Term Odanacatib Fracture Trial (LOFT) and its Extension

Odanacatib (ODN), a selective oral inhibitor of cathepsin K, was an investigational agent previously in development for the treatment of osteoporosis. In this analysis, the effects of ODN on bone remodeling/modeling and structure were examined in the randomized, double-blind, placebo-controlled, event-driven, Phase 3, Long-term Odanacatib Fracture Trial (LOFT; NCT00529373) and planned double-blind extension in postmenopausal women with osteoporosis. A total of 386 transilial bone biopsies, obtained from consenting patients at baseline (ODN n = 17, placebo n = 23), month 24 (ODN n = 112, placebo n = 104), month 36 (ODN n = 42, placebo n = 41), and month 60 (ODN n = 27, placebo n = 20) were assessed by dynamic and static bone histomorphometry. Patient characteristics at baseline and BMD changes over 5 years for this subset were comparable to the overall LOFT population. Qualitative assessment of biopsies revealed no abnormalities. Consistent with the mechanism of ODN, osteoclast number was higher with ODN versus placebo over time. Regarding bone remodeling, dynamic bone formation indices in trabecular, intracortical, and endocortical surfaces were generally similar in ODN-treated versus placebo-treated patients after 2 years of treatment. Regarding periosteal modeling, the proportion of patients with periosteal double labels and the bone formation indices increased over time in the ODN-treated patients compared with placebo. This finding supported the observed numerical increase in cortical thickness at month 60 versus placebo. In conclusion, ODN treatment for 5 years did not reduce bone remodeling and increased the proportion of patients with periosteal bone formation. These results are consistent with the mechanism of action of ODN, and are associated with continued BMD increases and reduced risk of fractures compared with placebo in the LOFT Phase 3 fracture trial. © 2020 American Society for Bone and Mineral Research.     

Acetylcholinesterase Inhibitors Are Associated with Reduced Fracture Risk among Older Veterans with Dementia

Acetylcholinesterase inhibitors (AChEIs) have been noted to increase bone density and quality in mice. Human studies are limited but suggest an association with improved bone healing after hip fracture. We examined the relationship between AChEI use and fracture risk in a national cohort of 360,015 male veterans aged 65 to 99 years with dementia but without prior fracture using Veterans Affairs (VA) hospital, Medicare, and pharmacy records from 2000 to 2010. Diagnosis of dementia, any clinical fracture (excluding facial and digital), comorbidities, and medications were identified using ICD-9 and drug class codes. Cox proportional hazard models considering AChEI use as a time-varying covariate and adjusting for fall and fracture risk factors compared the time-to-fracture in AChEI users versus non-AChEI users. Potential confounders included demographics (age, race, body mass index), comorbidities associated with fracture or falls (diabetes, lung disease, stroke, Parkinson's, seizures, etc.) and medications associated with fracture or falls (bisphosphonates, glucocorticoids, androgen deprivation therapy [ADT], proton pump inhibitors [PPIs], selective serotonin receptor inhibitors [SSRIs], etc.). Competing mortality risk was considered using the methods of Fine and Gray. To account for persistent effects on bone density or quality that might confer protection after stopping the medication, we completed a secondary analysis using the medication possession ratio (MPR) as a continuous variable in logistic regression models and also compared MPR increments of 10% to minimal/no use (MPR 0 to <0.10). Among older veterans with diagnosis of dementia, 20.1% suffered a fracture over an average of 4.6 years of follow-up. Overall, 42.3% of the cohort were prescribed AChEIs during the study period. The hazard of any fracture among AChEI users compared with those on other/no dementia medications was significantly lower in fully adjusted models (hazard ratio [HR] = 0.81; 95% confidence interval [CI] 0.75–0.88). After considering competing mortality risk, fracture risk remained 18% lower in veterans using AChEIs (HR = 0.82; 95% CI 0.76–0.89). © 2019 American Society for Bone and Mineral Research. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.