Deciphering osteoarthritis genetics across 826,690 individuals from 9 populations.

Osteoarthritis affects over 300 million people worldwide. Here, we conduct a genome-wide association study meta-analysis across 826,690 individuals (177,517 with osteoarthritis) and identify 100 independently associated risk variants across 11 osteoarthritis phenotypes, 52 of which have not been associated with the disease before. We report thumb and spine osteoarthritis risk variants and identify differences in genetic effects between weight-bearing and non-weight-bearing joints. We identify sex-specific and early age-at-onset osteoarthritis risk loci. We integrate functional genomics data from primary patient tissues (including articular cartilage, subchondral bone, and osteophytic cartilage) and identify high-confidence effector genes. We provide evidence for genetic correlation with phenotypes related to pain, the main disease symptom, and identify likely causal genes linked to neuronal processes. Our results provide insights into key molecular players in disease processes and highlight attractive drug targets to accelerate translation.

PPARGC1B Is Associated with Nontraumatic Osteonecrosis of the Femoral Head: A Genomewide Association Study on a Chart-Reviewed Cohort.

BACKGROUND: Previous studies have demonstrated the influence of heritable factors on the development of nontraumatic osteonecrosis of the femoral head (ONFH). We hypothesized that genetic variation is associated with an increased risk of ONFH, and that variants could be identified by a genomewide association study (GWAS). METHODS: Using data collected from the MyCode Community Health Initiative, we identified 118 adult patients with radiographically confirmed nontraumatic ONFH. Study patients were statistically compared with a control population of 56,811 unrelated individuals without a diagnosis of ONFH. A case-control GWAS was performed to identify single nucleotide variants (SNVs) associated with ONFH. Sensitivity analyses were performed to evaluate the association of the top SNVs with (cortico)steroid-associated ONFH and ONFH with femoral head collapse. Gene-based analyses were performed to identify potential causal genes. RESULTS: Of the 118 patients, 114 (96.6%) had bilateral ONFH at a median of 5 years of follow-up; 90.7% had at least one 3-week steroid prescription compared with 68.3% in controls. A GWAS identified 4 SNVs reaching genomewide significance. rs116468452 near CACNA1E was significantly associated with ONFH (p = 3.26 × 10, odds ratio [OR] = 5.6, 95% confidence interval [CI] = 3.21 to 9.76). rs10953090 in SAMD9 was significantly associated with ONFH in the steroid-exposed subset (p = 2.96 × 10, OR = 2.57, 95% CI = 1.84 to 3.58). rs112467115 in PI4K1B showed enhanced association in the collapsed subset (p = 7.82 × 10, OR = 4.5, 95% CI = 2.60 to 7.79). Gene-based analyses identified PPARGC1B as the only gene significantly associated with ONFH after Bonferroni correction (p = 1 × 10), with the lead SNV being rs78814834 (OR = 2.86, 95% CI = 1.87 to 4.38). CONCLUSIONS: We identified 4 SNVs and 1 gene, PPARGC1B, associated with ONFH. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Articular cartilage repair: Current needs, methods and research directions.

Articular cartilage is a highly specialized tissue whose remarkable properties of deformability, resistance to mechanical loading, and low-friction gliding are essential to joint function. Due to its role as a cushion in bone articulation, articular cartilage is subject to many types of damaging insults, including decades of wear and tear, and acute joint injuries. However, this built-for-life tissue has a very poor intrinsic ability in adulthood to durably heal defects created by damaging insults. Consequently, articular cartilage progressively deteriorates and is eventually eroded, exposing the subchondral bone to the joint space, triggering inflammation and osteophyte development, and generating severe pain and joint incapacitation. The disease is called osteoarthritis (OA) and is today the leading cause of pain and disability in the human population. Researchers and clinicians have worked for decades to develop strategies to treat OA and restore joint function, but they are still far from being able to offer patients effective preventive or restorative treatments. Novel ideas, knowledge and technologies that nurture hope for major new breakthroughs are therefore sought. In this review, we first outline the composition, structure, and functional properties of normal human adult articular cartilage, as a reference for tissue conservation and regenerative strategies. We then describe current options that have been used clinically and in pre-clinical trials to treat osteoarthritic patients, and we discuss the benefits and inadequacies of these treatment options. Next, we review research efforts that are currently ongoing to try and achieve durable repair of functional cartilage tissue. Methods include engineering of tissue implants and we discuss the needs and options for tissue scaffolds, cell sources, and growth and differentiation factors to generate de novo or repair bona fide articular cartilage.

Complications With Long Cemented Stems in Proximal Femoral Replacement.

This study attempted to determine whether patients undergoing cemented long-stem proximal femoral replacement had: (1) an increased short-term mortality rate; (2) greater intraoperative hemodynamic instability; (3) a greater need for resuscitation; and (4) a decreased risk of periprosthetic fracture. The current study reviewed intraoperative and short-term events related to clinical outcomes in 24 consecutive patients who were treated at a single institution over a 5-year period. These patients underwent primary long-stem (≥250 mm, n=13) vs short-stem (<250 mm, n=11) cemented proximal femoral replacement. Other than stem length, the 2 groups were not significantly different in terms of patient age, sex, height, weight, body mass index, diagnosis, or preoperative American Society of Anesthesiologists functional score. Primary outcomes were intraoperative death, blood loss, blood transfusions, fluid resuscitation, hypotension, oxygen desaturation, mortality up to 1 year, and need for revision surgery. At 1 year, a significantly increased mortality rate (77% vs 27%, P=.03) was noted in patients receiving long-stem vs short-stem arthroplasty. Patients who received longer stems also required more intraoperative blood transfusions and fluid resuscitation (P=.04) for greater hypotension (P=.04) and oxygen desaturation (P=.04). Two intraoperative deaths occurred in the long-stem group, and none occurred in the short-stem group. The findings suggest that there is an increased risk of intraoperative hemodynamic instability with long-stem vs short-stem proximal femoral replacement, with a need for greater resuscitative efforts and an increased risk of mortality at 1 year. [Orthopedics. 2016; 39(3):e423-e429.].

Induced pluripotent stem cells in cartilage repair.

Articular cartilage repair techniques are challenging. Human embryonic stem cells and induced pluripotent stem cells (iPSCs) theoretically provide an unlimited number of specialized cells which could be used in articular cartilage repair. However thus far chondrocytes from iPSCs have been created primarily by viral transfection and with the use of cocultured feeder cells. In addition chondrocytes derived from iPSCs have usually been formed in condensed cell bodies (resembling embryoid bodies) that then require dissolution with consequent substantial loss of cell viability and phenotype. All of these current techniques used to derive chondrocytes from iPSCs are problematic but solutions to these problems are on the horizon. These solutions will make iPSCs a viable alternative for articular cartilage repair in the near future.

Fibrous dysplasia.

Fibrous dysplasia is a developmental abnormality of bone that is characterized by a highly disorganized mixture of immature fibrous tissue and fragments of immature trabecular bone. Fibrous dysplasia may arise as a single, discrete (monostotic) lesion or can occur with a more widespread distribution with multiple lesions that affect many bones (oligo- or polyostotic). Fibrous dysplasia is usually an isolated skeletal finding but can sometimes occur as a component of a multisystem developmental disorder known as McCune-Albright syndrome (MAS) that is also associated with endocrine hyperfunction (e.g. precocious puberty) and caf au lait cutaneous macules. The identification of activating mutations in GNAS in a subset of human GH-secreting pituitary tumors and autonomously functioning human thyroid tumors provided the initial basis for understanding the molecular pathophysiology of McCune-Albright syndrome and fibrous dysplasia. These observations led to the concept that activating mutations of the GNAS gene convert it into a putative oncogene referred to as gsp (Gsa or Gas). The classic radiographic feature of fibrous dysplasia is a hazy, radiolucent, or ground-glass, pattern resulting from the defective mineralization of immature dysplastic bone; it is usually strikingly different from the radiographic appearance of normal bone, calcified cartilage, or soft tissue. The surgical approach to fibrous dysplasia should in general be conservative. Recent research suggests that the WntlB-catenin pathway may play a role in fibrous dysplasia as patients with activating GNAS mutations specifically showed that Gas mutations activated Wnt/B-catenin signaling. Thus inhibition of 8-catenin signaling or silencing GNAS alleles that encode constitutively active Gsa molecules in fibrous dysplasia and McCune-Albright syndrome offer potential therapeutic promise and deserve further study. In summary fibrous dysplasia is a developmental abnormality of bone with a known molecular etiology; Further knowledge about the molecular pathology of fibrous dysplasia may lead to improved conservative therapies in the near future.

Cloning and characterization of the human SH3BP2 promoter.

SH3BP2 activating mutations lead to an unique clinical condition in which patients develop symmetrical bone resorptive lesions of the jaw, a condition termed cherubism. Due to this specific temporal sequence and location of bone resorption, we investigated the transcriptional regulation of SH3BP2 expression. Analyses of 5'- and 3'-serial promoter deletions defined the core promoter/regulatory elements, including two repressor sites (from -1,200 to -1,000 and from +86 to +115, respectively) and two activator sites (a PARP1 binding site from -44 to -21 and a second activator site from +57 to +86). We identified that PARP1 binds to DNA from -44 to -21 by Streptavidin-biotin purification and confirmed this binding by electrophoretic mobility shift assay (EMSA). Mutagenesis of the PARP1 binding site on the SH3BP2 promoter showed that this binding site is essential for SH3BP2 expression. EMSA and chromatin immunoprecipitation (ChIP) assays confirmed that PARP1 was able to bind to the SH3BP2 promoter in vitro and in vivo. Indeed, knockout of Parp1 in mice BMMs reduced expression of SH3BP2. These results demonstrate that PARP1 regulates expression of SH3BP2.

Cherubism: best clinical practice.

Cherubism is a skeletal dysplasia characterized by bilateral and symmetric fibro-osseous lesions limited to the mandible and maxilla. In most patients, cherubism is due to dominant mutations in the SH3BP2 gene on chromosome 4p16.3. Affected children appear normal at birth. Swelling of the jaws usually appears between 2 and 7 years of age, after which, lesions proliferate and increase in size until puberty. The lesions subsequently begin to regress, fill with bone and remodel until age 30, when they are frequently not detectable.Fibro-osseous lesions, including those in cherubism have been classified as quiescent, non-aggressive and aggressive on the basis of clinical behavior and radiographic findings. Quiescent cherubic lesions are usually seen in older patients and do not demonstrate progressive growth. Non-aggressive lesions are most frequently present in teenagers. Lesions in the aggressive form of cherubism occur in young children and are large, rapidly growing and may cause tooth displacement, root resorption, thinning and perforation of cortical bone.Because cherubism is usually self-limiting, operative treatment may not be necessary. Longitudinal observation and follow-up is the initial management in most cases. Surgical intervention with curettage, contouring or resection may be indicated for functional or aesthetic reasons. Surgical procedures are usually performed when the disease becomes quiescent. Aggressive lesions that cause severe functional problems such as airway obstruction justify early surgical intervention.

The role of SH3BP2 in the pathophysiology of cherubism.

Cherubism is a rare bone dysplasia that is characterized by symmetrical bone resorption limited to the jaws. Bone lesions are filled with soft fibrous giant cell-rich tissue that can expand and cause severe facial deformity. The disorder typically begins in children at ages of 2-5 years and the bone resorption and facial swelling continues until puberty; in most cases the lesions regress spontaneously thereafter. Most patients with cherubism have germline mutations in the gene encoding SH3BP2, an adapter protein involved in adaptive and innate immune response signaling. A mouse model carrying a Pro416Arg mutation in SH3BP2 develops osteopenia and expansile lytic lesions in bone and some soft tissue organs. In this review we discuss the genetics of cherubism, the biological functions of SH3BP2 and the analysis of the mouse model. The data suggest that the underlying cause for cherubism is a systemic autoinflammatory response to physiologic challenges despite the localized appearance of bone resorption and fibrous expansion to the jaws in humans.

Preimplantation genetic diagnosis for hereditary endocrine disease.

OBJECTIVE: To describe the process of preimplantation genetic diagnosis (PGD), which allows the selection of embryos without mutations for implantation, with specific application for mutations in GNAS. METHODS: We identified a GNAS mutation in a patient with a severe form of Albright hereditary osteodystrophy and pseudohypoparathyroidism type 1a with phocomelia and performed PGD on embryos derived by in vitro fertilization in order to deliver an unaffected infant. RESULTS: After in vitro fertilization, embryos that were homozygous normal for GNAS were identified and implanted into the mother. Ultrasonography 34 days after embryo transfer showed a viable singleton intrauterine pregnancy. A normal-appearing male infant was born at 36.5 weeks of gestation. Newborn screening revealed normal results of thyroid function tests, and a buccal swab obtained when the child was 1 year old verified normal GNAS gene sequences. CONCLUSION: PGD is an alternative that can be offered for many genetic diseases and represents a method to decrease and potentially eliminate the transmission of severe genetic diseases. Patients with multiple endocrine neoplasia (MEN) type 2 with known RET gene mutations as well as those with other heritable disorders are candidates for PGD. Successful PGD in patients with MEN has not yet been reported and has met with some early difficulties, but it is believed that this technique will eventually be successful for MEN and other hereditary endocrine disorders.

Decreased SH3BP2 inhibits osteoclast differentiation and function.

Germline mutations in SH3BP2 gene have been identified in patients with cherubism, a skeletal disorder characterized by excessive osteoclastic bone resorption that is limited to the mandible and maxilla. We previously demonstrated that SH3BP2 overexpression in Raw264.7 cells increased RANKL-induced osteoclastogenesis. Here, we examine the effect of decreased SH3BP2 on osteoclastogenesis. shRNA knockdown of SH3BP2 decreased PLCγ2 phosphorylation and NFATc1 expression, and reduced the expression of osteoclast-specific genes. In BMMs knockdown of SH3BP2 led to reductions in both the number and the surface area of TRAP positive and multinucleated osteoclasts. Bone resorptive activity was also dramatically blocked by shRNA knockdown of SH3BP2. Similarly Sh3bp2(-/-) deficient mice BMMs formed smaller osteoclasts that stained less with TRAP than wild-type mice. Taken together, this study demonstrates that SH3BP2 knockdown significantly decreases osteoclast differentiation and function. These results suggest that SH3BP2 plays a critical role in osteoclastogenesis and is a potential target for suppression of pathologic bone resorption.

Prognosticators in thigh soft tissue sarcomas.

BACKGROUND: In sarcoma patients the roles of smoking history, family cancer history, and leukoreduced blood transfusions have not been studied and the effect of preoperative radiation on blood loss has not been examined. METHODS: Seventy-seven patients with non-metastatic and non-recurrent thigh sarcomas surgically treated at the Cleveland Clinic were identified. Among patient variables studied were: close family history of cancer, perioperative transfusion history, smoking history, and radiation history. Median follow-up for the survivors was 3.2 years. RESULTS: We found that tumor grade, transfusion >3 U (P = 0.022), and pre- or post-operative radiation therapy (P = 0.041) were risk factors for distant metastasis. Tumor grade (P = 0.008), positive smoking history (P = 0.039), and >3 U of non-leukoreduced blood transfused (P = 0.037) were risk factors for death of any-cause. Close family history of cancer correlated with having a grade 3 sarcoma (P = 0.044). Neoadjuvant radiotherapy correlated with >3 U of blood transfused (P = 0.001) and biopsy performed at the treating institution led to a significant decrease in rate of recurrence (P = 0.016). CONCLUSIONS: We present novel findings in terms of transfusions, family history of cancer and site of initial biopsy in sarcoma patients.

SH3BP2 mutations potentiate osteoclastogenesis via PLCγ.

To determine the mechanism for the increased osteoclastogenesis in the jaw of cherubism patients with SH3BP2 mutations we evaluated the effect of mutant compared to wild-type SH3BP2 on activation of osteoclast signaling pathways. Indeed mutant forms of SH3BP2 do induce greater osteoclastogenesis. Heterozygous activating mutations in exon 9 of SH3BP2 have been found in most patients with cherubism, an unusual genetic syndrome characterized by excessive remodeling of the mandible and maxilla due to spontaneous and excessive osteoclastic bone resorption. Here we have investigated the functional consequences of SH3BP2 mutations on sRANKL-induced osteoclastogenesis in RAW 264.7 pre-osteoclast cells. sRANKL-stimulated RAW 264.7 cells were transfected with wild-type or mutant SH3BP2 plasmids. NFAT-luciferase and tartrate resistant acid phosphatase (TRAP), a marker of osteoclastic differentiation, levels were evaluated. Western immunoblots were also performed to determine phosphorylation of key proteins involved in the PI-PLC pathway leading to NFATc1 translocation. Our results indicate that forced expression of mutant forms of SH3BP2, found in cherubism patients, in RAW 264.7 cells induce greater NFAT activity and greater expression of TRAP than forced expression of wild-type SH3BP2. These findings indicate that missense SH3BP2 mutations cause a gain of protein function. Moreover, over expression of SH3BP2 in RAW 264.7 cells potentiates sRANKL-stimulated phosphorylation of PLCγ1 and PLCγ2. Our studies demonstrate that cherubism is due to gain-of-function mutations in SH3BP2 that stimulate RANKL-induced activation of PLCγ. The consequent activation of calcineurin and NFAT proteins induces the excessive osteoclastic phenotype of cherubism.

Hypercalcemia in children and adolescents.

PURPOSE OF REVIEW: In this review, we define hypercalcemia levels, common causes for hypercalcemia in children, and treatment in order to aid the practicing pediatrician. RECENT FINDINGS: One rare cause of hypercalcemia in the child is familial hypocalciuric hypercalcemia (also termed familial benign hypercalcemia). Mutations that inactivate the Ca-sensing receptor gene FHH have been described as an autosomal dominant disorder, but recently milder mutations in the CASR have been shown to cause hypercalcemia when homozygous. SUMMARY: Normal serum levels of calcium are maintained through the interplay of parathyroid, renal, and skeletal factors. In this review, we have distinguished the neonate and infant from the older child and adolescent because the causes and clinical features of hypercalcemia can differ in these two age groups. However, the initial approach to the medical treatment of severe or symptomatic hypercalcemia is to increase the urinary excretion of calcium in both groups. In most cases, hypercalcemia is due to osteoclastic bone resorption, and agents that inhibit or destroy osteoclasts are, therefore, effective treatments. Parathyroid surgery, the conventional treatment for adults with symptomatic primary hyperparathyroidism, is recommended for all children with primary hyperparathyroidism.

Soft-tissue sarcomas: Overview of management, with a focus on surgical treatment considerations.

Patients with soft-tissue sarcomas generally present with a mass that is increasing in size; the presence or absence of pain is not typically predictive of malignancy. While magnetic resonance imaging (MRI) can identify a few soft-tissue lesion types as benign, diagnosis of most lesions requires a careful biopsy, preferably performed by or in consultation with the surgeon who would do an eventual resection. If biopsy confirms a diagnosis of sarcoma, MRI-guided surgical resection with a wide margin is the mainstay of treatment. Neoadjuvant radiation therapy and chemotherapy have not been of proven benefit in well-controlled studies but are frequently used as adjuncts. Resections with wide margins are generally associated with a low (< 10%) risk of recurrence.

Clinical presentation and imaging of bone and soft-tissue sarcomas.

The clinical presentation of bone and soft-tissue sarcomas is varied. Constitutional symptoms are rare, and although bone sarcomas tend to be painful while soft-tissue sarcomas usually are not, there are exceptions to this general rule. A high index of suspicion is required for any unexplained mass with indeterminate imaging findings. Choosing the right imaging modality is critical to the diagnosis and management of patients with suspected sarcoma, and referring clinicians have a multitude of imaging options. After discovery of a malignant-appearing bone lesion by radiography, further imaging is obtained for better characterization of the lesion (typically with magnetic resonance imaging [MRI]) and for staging (typically with computed tomography of the chest). In contrast, radiographs are rarely helpful for evaluation of soft-tissue lesions, which almost always require MRI assessment.

Bone sarcomas: Overview of management, with a focus on surgical treatment considerations.

Outcomes for patients with bone sarcomas have improved dramatically over the past 40 years, and most bone sarcomas today are treated with surgery and chemotherapy. The most common clinical findings in patients with bone sarcomas are pain and an enlarging bone mass, although pain is not generally a good indicator of malignancy. In general, any patient with a bone mass with indeterminate imaging findings should be referred to an orthopedic oncologist. Bone sarcomas are diagnosed after a biopsy, which is best performed by the surgeon who will be doing the curative resection. Postresection reconstruction of the affected limb is generally done with an allograft-prosthetic composite or a modular metallic prosthetic joint replacement device. Post-therapy follow-up at frequent and regular intervals is critical to assess for recurrence and lung metastasis.