Somatic uniparental disomy mitigates the most damaging EFL1 allele combination in Shwachman-Diamond syndrome.

Shwachman-Diamond syndrome (SDS; OMIM #260400) is caused by variants in SBDS (Shwachman-Bodian-Diamond syndrome gene), which encodes a protein that plays an important role in ribosome assembly. Recent reports suggest that recessive variants in EFL1 are also responsible for SDS. However, the precise genetic mechanism that leads to EFL1-induced SDS remains incompletely understood. Here we present 3 unrelated Korean SDS patients who carry biallelic pathogenic variants in EFL1 with biased allele frequencies, resulting from a bone marrow-specific somatic uniparental disomy in chromosome 15. The recombination events generated cells that were homozygous for the relatively milder variant, allowing for the evasion of catastrophic physiologic consequences. However, the milder EFL1 variant was still solely able to impair 80S ribosome assembly and induce SDS features in cell line and animal models. The loss of EFL1 resulted in a pronounced inhibition of terminal oligopyrimidine element-containing ribosomal protein transcript 80S assembly. Therefore, we propose a more accurate pathogenesis mechanism of EFL1 dysfunction that eventually leads to aberrant translational control and ribosomopathy.

Most Fractures Treated Nonoperatively in Individuals With Fibrodysplasia Ossificans Progressiva Heal With a Paucity of Flareups, Heterotopic Ossification, and Loss of Mobility.

BACKGROUND: Fibrodysplasia ossificans progressiva (FOP) is an ultrarare genetic disorder with episodic and progressive heterotopic ossification. Tissue trauma is a major risk factor for flareups, heterotopic ossification (HO), and loss of mobility in patients with FOP. The International Clinical Council on FOP generally recommends avoiding surgery in patients with FOP unless the situation is life-threatening, because soft tissue injury can trigger an FOP flareup. Surprisingly little is known about flareups, HO formation, and loss of mobility after fractures of the normotopic (occurring in the normal place, distinct from heterotopic) skeleton when treated nonoperatively in patients with FOP. QUESTIONS/PURPOSES: (1) What proportion of fractures had radiographic evidence of union (defined as radiographic evidence of healing at 6 weeks) or nonunion (defined as the radiographic absence of a bridging callus at 3 years after the fracture)? (2) What proportion of patients had clinical symptoms of an FOP flareup because of the fracture (defined by increased pain or swelling at the fracture site within several days after closed immobilization)? (3) What proportion of patients with fractures had radiographic evidence of HO? (4) What proportion of patients lost movement after a fracture? METHODS: We retrospectively identified 36 patients with FOP from five continents who sustained 48 fractures of the normotopic skeleton from January 2001 to February 2021, who were treated nonoperatively, and who were followed for a minimum of 18 months after the fracture and for as long as 20 years, depending on when they sustained their fracture during the study period. Five patients (seven fractures) were excluded from the analysis to minimize cotreatment bias because these patients were enrolled in palovarotene clinical trials (NCT02190747 and NCT03312634) at the time of their fractures. Thus, we analyzed 31 patients (13 male, 18 female, median age 22 years, range 5 to 57 years) who sustained 41 fractures of the normotopic skeleton that were treated nonoperatively. Patients were analyzed at a median follow-up of 6 years (range 18 months to 20 years), and none was lost to follow-up. Clinical records for each patient were reviewed by the referring physician-author and the following data for each fracture were recorded: biological sex, ACVR1 gene pathogenic variant, age at the time of fracture, fracture mechanism, fracture location, initial treatment modality, prednisone use at the time of the fracture as indicated in the FOP Treatment Guidelines for flare prevention (2 mg/kg once daily for 4 days), patient-reported flareups (episodic inflammatory lesions of muscle and deep soft connective tissue characterized variably by swelling, escalating pain, stiffness, and immobility) after the fracture, follow-up radiographs of the fracture if available, HO formation (yes or no) as a result of the fracture determined at a minimum of 6 weeks after the fracture, and patient-reported loss of motion at least 6 months after and as long as 20 years after the fracture. Postfracture radiographs were available in 76% (31 of 41) of fractures in 25 patients and were independently reviewed by the referring physician-author and senior author for radiographic criteria of fracture healing and HO. RESULTS: Radiographic healing was noted in 97% (30 of 31) of fractures at 6 weeks after the incident fracture. Painless nonunion was noted in one patient who sustained a displaced patellar fracture and HO. In seven percent (three of 41) of fractures, patients reported increased pain or swelling at or near the fracture site within several days after fracture immobilization that likely indicated a site-specific FOP flareup. The same three patients reported a residual loss of motion 1 year after the fracture compared with their prefracture status. HO developed in 10% (three of 31) of the fractures for which follow-up radiographs were available. Patient-reported loss of motion occurred in 10% (four of 41) of fractures. Two of the four patients reported noticeable loss of motion and the other two patients reported that the joint was completely immobile (ankylosis). CONCLUSION: Most fractures treated nonoperatively in individuals with FOP healed with few flareups, little or no HO, and preservation of mobility, suggesting an uncoupling of fracture repair and HO, which are two inflammation-induced processes of endochondral ossification. These findings underscore the importance of considering nonoperative treatment for fractures in individuals with FOP. Physicians who treat fractures in patients with FOP should consult with a member of the International Clinical Council listed in the FOP Treatment Guidelines ( https://www.iccfop.org ). LEVEL OF EVIDENCE: Level IV, therapeutic study.

The role of 99mTc-DPD bone SPECT/CT in the management of growth disturbance of the long bones in pediatric patients: a retrospective observational study.

BACKGROUNDS: Determining the precise localization of diseased physes is crucial for guiding the treatment of growth disturbances. Conventional radiography, computed tomography (CT), and magnetic resonance imaging only provide information on physeal anatomy. Planar bone scintigraphy and bone single-photon emission computed tomography (SPECT) resolutions are suboptimal for clinically managing growth disturbances. Bone SPECT/CT, which provides high-resolution functional information, can be a useful tool for evaluating growth disturbances. The purposes of this study were to identify the conditions in which bone SPECT/CT outperforms planar scintigraphy or SPECT for evaluating the location and activity of diseased physes and to assess surgical outcomes using bone SPECT/CT findings in pediatric patients experiencing long bone growth disturbances. METHODS: Fifty-nine patients who underwent bone SPECT/CT between January 2018 and January 2021 to evaluate physeal activity using technetium-99 m-labeled 2,3-dicarboxypropane-1,1-diphosphonate (99mTc-DPD) were included. The proportions of patients for whom certain modalities provided sufficient data for selecting treatment plans for growth disturbances were compared based on the site of the diseased physis, growth disturbance cause, and shape of deformity (i.e., SPECT/CT vs. planar scintigraphy and SPECT/CT vs. SPECT). For assessing surgical outcomes, progression of post-surgical deformity was investigated by measuring the angles reflecting the degree of deformity, iliac crest height difference, or ulnar variance on radiographs. RESULTS: Bone SPECT/CT was sufficient for selecting a treatment plan, but planar scintigraphy or SPECT alone was insufficient in every 10 patients with diseased physes inside the femoral head (p = 0.002) and in every six with physes that were severely deformed or whose locations were unclear on conventional radiography (p = 0.03). In the proximal or distal tibia, where the tibial and fibular physes often overlapped on planar scintigraphy due to leg rotation, bone SPECT/CT was sufficient in 33/34 patients (97%), but planar scintigraphy and SPECT were sufficient in 10/34 (29%) (p < 0.001) and 24/34 (71%) patients, respectively (p = 0.004). No progression or deformity recurrence occurred. CONCLUSIONS: Bone SPECT/CT may be indicated in proximal femoral growth disturbance, when the physis is unclear on conventional radiography or severely deformed, the leg exhibits rotational deformity, or the patient is noncompliant.

When to Combine Acetabular Osteotomy in Patients With Proximal Femoral Deformity Causing Residual Hip Dysplasia/Subluxation After Reduction of Developmental Dysplasia of the Hip.

BACKGROUND: After the successful reduction of developmental dysplasia of the hip, residual hip dysplasia may persist and lead to early osteoarthritis. Femoral and/or acetabular osteotomy has been used to address this problem. The purpose of this study is to determine the indication of femoral versus combined femoral-acetabular osteotomy in the management of residual hip dysplasia. METHODS: Fifty-five patients with unilateral dislocated-type dysplasia of the hip, who had residual hip dysplasia after reduction, underwent femoral osteotomy with or without acetabular osteotomy before 8 years of age, and were followed for more than 2 years and over 8 years of age, were the subjects of this retrospective study. Twenty-eight patients underwent femoral osteotomy only at a median age of 34 months (group F), and 27 underwent combined femoral-Dega osteotomy at a median age of 49 months (group C). Seventeen patients in group F and 4 in group C had an additional osteotomy due to persistent hip dysplasia. Acetabular index (AI), lateral center-edge angle, and center-head distance difference were measured on serial radiographs. The z-value of AI (Z AI ) was calculated. At the latest follow-up, patients in group F with Severin I/II who did not have an additional osteotomy were considered satisfactory, and patients with Severin III/IV or those who had an additional osteotomy were considered unsatisfactory. Preoperative variables were tested for the difference between satisfactory and unsatisfactory cases. Receiver operating characteristic analysis was performed to delineate a cutoff value of a significant parameter dividing the outcome. RESULTS: AI and Z AI before index osteotomy were significant parameters predicting a satisfactory outcome in group F. Receiver operating characteristic analysis returned a cutoff value of Z AI 2.6 (Area Under the Curve=0.86, P =0.001). Eight of 12 cases (66.7%) with Z AI <2.6 in group F achieved a satisfactory outcome, whereas only 2 of 14 cases with Z AI ≥2.6 in group F did ( P =0.02). CONCLUSION: Z AI 2.6 may serve as a threshold to combine acetabular osteotomy with femoral osteotomy in the management of residual hip dysplasia before 8 years of age. LEVEL OF EVIDENCE: Therapeutic III.

Hypomorphic Mutations in TONSL Cause SPONASTRIME Dysplasia.

SPONASTRIME dysplasia is a rare, recessive skeletal dysplasia characterized by short stature, facial dysmorphism, and aberrant radiographic findings of the spine and long bone metaphysis. No causative genetic alterations for SPONASTRIME dysplasia have yet been determined. Using whole-exome sequencing (WES), we identified bi-allelic TONSL mutations in 10 of 13 individuals with SPONASTRIME dysplasia. TONSL is a multi-domain scaffold protein that interacts with DNA replication and repair factors and which plays critical roles in resistance to replication stress and the maintenance of genome integrity. We show here that cellular defects in dermal fibroblasts from affected individuals are complemented by the expression of wild-type TONSL. In addition, in vitro cell-based assays and in silico analyses of TONSL structure support the pathogenicity of those TONSL variants. Intriguingly, a knock-in (KI) Tonsl mouse model leads to embryonic lethality, implying the physiological importance of TONSL. Overall, these findings indicate that genetic variants resulting in reduced function of TONSL cause SPONASTRIME dysplasia and highlight the importance of TONSL in embryonic development and postnatal growth.

Effect of Leg Length Discrepancy on Lateral Center-edge Angle Measurement.

BACKGROUND: In patients with leg length discrepancy (LLD) and consequent pelvic obliquity, either the longitudinal axis of the pelvis or a line perpendicular to the ground may be used as the longitudinal reference line for measuring the lateral center-edge angle (LCEA). We aimed to (1) systematically inspect which longitudinal reference line has been used for measuring the LCEA in previous studies; (2) evaluate the frequency of change in the radiographical classification of acetabular overcoverage or undercoverage per the longitudinal reference line; and (3) validate the trigonometric method, predicting the change in the LCEA according to the LLD. METHODS: Studies investigating the LCEA published between January 1976 and July 2019 in the MEDLINE database were categorized according to the longitudinal reference line used. Further, in a retrospective analysis of 238 patients surgically treated for LLD, the LCEA was first measured on standing pelvic radiographs using the longitudinal axis of the pelvis (pLCEA) and measured again using a line perpendicular to the ground (gLCEA). Femoral head coverage was categorized as undercoverage, normal, or overcoverage based on the pLCEA and gLCEA. The theoretically calculated difference between the pLCEA and gLCEA (dLCEA) as determined using a trigonometric method was compared with the dLCEA measured on radiographs. RESULTS: Of 229 previous studies, 188 did not specify the longitudinal reference line. The number of patients who were diagnosed with acetabular overcoverage using the pLCEA and gLCEA was one and fourteen, respectively (P<0.001). The number of patients who were diagnosed with acetabular undercoverage using the pLCEA and gLCEA was one and zero, respectively (P=1.000). There was no difference (P=0.433) between the theoretically calculated (9±5 degrees) and measured (9±5 degrees) dLCEAs. CONCLUSIONS: The definition of the longitudinal reference line should be clarified when measuring the LCEA. The trigonometric method can accurately predict the change in the LCEA according to LLD in concentric hips without proximal femoral and pelvic deformities. LEVEL OF EVIDENCE: Level IV-diagnostic study.

Calcifying characteristics of peripheral vascular smooth muscle cells of chronic kidney disease patients with critical limb ischemia.

The role of vascular smooth muscle cells (VSMCs) in vascular calcification, which is related to chronic kidney disease (CKD), has been studied in greater detail in the major arteries relative to the peripheral arteries. We compared the calcifying characteristics of peripheral VSMCs relative to non-pathologic major VSMCs in patients with severe peripheral artery disease (PAD). We isolated peripheral VSMCs from the posterior tibial artery of 10 patients with CKD who underwent below-knee amputation for critical limb ischemia (CLI). Using normal human aortic VSMCs as a control group, we cultured the cells in normal and high phosphate media for 10 days, and subsequently tested by immunofluorescence staining. We compared the calcification levels between the two groups using various assays, tests for cell viability, and scanning electron microscopy. As a result, calcification of pathologic peripheral VSMCs increased significantly with time (p = 0.028) and was significantly higher than that in human aortic VSMCs in calcium assays (p = 0.043). Dead cells in the pathologic VSMC group were more distinct in high phosphate media than in human aortic VSMCs. In conclusion, VSMCs from the peripheral artery of patients with severe CKD and CLI who underwent amputation surgery showed marked calcifying characteristics compared to normal human aortic VSMCs.

Pseudo-Protrusio Acetabular Deformity in Osteogenesis Imperfecta Patients.

BACKGROUND: Osteogenesis imperfecta (OI) can develop a protrusio acetabuli deformity. However, the authors observed a pseudo-protrusio-type acetabular deformity (PPAD) on 3-dimensional computed tomography (3D-CT). Hence, we systematically reviewed 3D-CT and pelvis radiographs of OI patients and report the incidence and patterns of acetabular deformity in OI patients and the associated radiographic signs. METHODS: The study included 590 hips of 295 OI patients, who were older than 5 years, and did not have a pelvic fracture. The incidence of a deformed acetabulum (center-edge angle >40 degrees) and its correlation with disease severity were investigated. In 40 hips for which 3D-CT was available, 3-dimensional morphology of the acetabular deformity was analyzed to delineate PPAD. On plain radiographs, PPAD-related signs were determined, focusing on the contour of ilioischial line, iliopectineal line, acetabular line, and their relationship. These radiographic signs were also evaluated in the remaining hips with deformed acetabula that did not have 3D-CT. RESULTS: One hundred twenty-three hips of 590 hips (21%) showed deformed acetabula. The incidence of deformed acetabula was significantly associated with disease severity (P<0.001). Three-dimensional analysis showed that 10 hips had protrusio acetabuli, whereas 17 had PPAD, which showed that the hemipelvis was crumpled, the acetabular roof was rotated upwardly and medially, and the hip center migrated superiorly, uncovering the anterior femoral head. Among the PPAD-related signs, superomedial bulging of the iliopectineal line was the most predictive radiographic sign (73% sensitivity and 100% specificity). This sign was also observed in almost one third of deformed acetabula of those investigated only with plain radiographs. CONCLUSIONS: This study showed that acetabular deformity is common in OI patients and is associated with disease severity. A substantial number of hips showed PPAD, which may not cause femoroacetabular impingement but result in anterior uncovering of the hip joint. Superomedial bulging of the iliopectineal line suggests this pattern of acetabular deformity. LEVEL OF EVIDENCE: Lever IV-prognostic studies.

Parallel Multiparameter Study of PEI-Functionalized Gold Nanoparticle Synthesis for Biomedical Applications: Part 2. Elucidating the Role of Surface Chemistry and Polymer Structure in Performance.

Elucidating the polyethyleneimine (PEI) chemistry to predictively and reproducibly synthesize gold nanoparticle (AuNP)-PEI conjugates with desired properties has been elusive despite evaluation in numerous studies and reported enhanced properties. The lack of reproducible methods to control the core size and stability has led to contradictory results for performance and safety; thus, advancement of the conjugate platform for commercial use has likely been hindered. Recently, we reported a robust, reproducible method for synthesizing PEI-functionalized AuNPs (Au-PEIs), providing an opportunity to investigate structure-function relationships and to further investigate synthesis parameters affecting performance, where only materials stable in biological media are candidates for use. The properties of Au-PEIs prepared by the optimized reduction of HAuCl4 using four different structural variants of PEI changed significantly with the PEI molar mass and backbone form (branched or linear). In the present study using our previously reported synthesis procedure, comprehensive analysis of properties such as size distribution, surface plasmon resonance (SPR), morphological state, surface functionality, and the shelf life has been systematically evaluated to elucidate the role of surface chemistry and reactive groups involved in conjugation, as a function of conjugate size and morphology. Being important for commercial adoption, the chemistry was related to the observed colloidal stability of the product in relevant media, including exposure to physiological variables such as salt, pH, proteins, and thermal changes. Overall, this work advances progress toward smart design of engineered nanoscale drug delivery systems and devices by providing unreported details of contributions affecting formation, stability, and fate.

Which Acetabular Landmarks are the Most Useful for Measuring the Acetabular Index and Center-edge Angle in Developmental Dysplasia of the Hip? A Comparison of Two Methods.

BACKGROUND: The acetabular index and center-edge angle are widely used radiographic parameters. However, the exact landmarks for measuring these parameters are not clearly defined. Although their measurement is straightforward when the lateral osseous margin of the acetabular roof coincides with the lateral end of the acetabular sourcil, where these two landmarks disagree, recommendations have differed about which landmark should be used. Using a radiographic parameter with high reliability for predicting residual hip dysplasia helps avoid unnecessary treatment. QUESTIONS/PURPOSES: We aimed to (1) compare two landmarks (the lateral osseous margin of the acetabular roof and the lateral end of the acetabular sourcil) for measuring the acetabular index and center-edge angle with respect to intraobserver and interobserver reliability and the predictability of residual hip dysplasia in patients with developmental dysplasia of the hip (DDH) and (2) evaluate longitudinal change in the acetabular edge's shape after closed reduction with the patient under general anesthesia. METHODS: Between February 1985 and July 2006, we performed closed reduction with the patient under general anesthesia as well as cast immobilization in 116 patients with DDH. To be included in this study, a patient had to have dislocated-type DDH. We excluded patients with a hip dislocation associated with neuromuscular disease, arthrogryposis, or congenital anomalies of other organs or systems (n = 9); hips that underwent osteotomy within 1 year since closed reduction (n = 8); hips that underwent open reduction because of re-dislocation after closed reduction (n = 4); and hips with Type III or IV osteonecrosis according to Bucholz-Ogden's classification (n = 4). Ninety-one patients were eligible. We excluded 19% (17 of 91) of the patients, who were lost to follow-up before they were 8 years old, leaving 81% (74 of 91 patients) with full preoperative and most-recent data. Ninety-seven percent (72 patients) were girls and 3% (two patients) were boys. The mean ± standard deviation age was 14.0 months ± 6.4 months (range 3-40 months) at the time of closed reduction and 12.1 years ± 2.3 years (range 8.0-16.0 years) at the time of the latest follow-up examination, the duration of which averaged 11 years ± 2.2 years (range 6.5-15.4 years). To investigate whether longitudinal change in the acetabular edge's shape differed among hips with DDH, contralateral hips, and control hips, we identified control participants after searching our hospital's database for patients with a diagnosis of congenital idiopathic hemihypertrophy from October 2000 to November 2006 who had AP hip radiographs taken at 3 years old and then at older than 8 years. From 29 patients who met these criteria, we randomly excluded two male patients to match for sex because girls were predominant in the DDH group. We excluded another female patient from the control group because of a hip radiograph that revealed unacceptable rotation. Eventually, 26 patients were assigned to the control group. Control patients consisted of 24 girls (92%) and two boys (8%). The demographic characteristics of control patients was not different from those of 67 patients with unilateral DDH, except for laterality (left-side involvement: 64% [43 of 67] in the DDH group versus 38% [10 of 26] in the control group; odds ratio 1.7 [95% confidence interval, 1.0-2.8]; p = 0.035). The acetabular index and center-edge angle at 3 years old were measured using the lateral osseous margin of the acetabular roof (AIB and CEAB) and the lateral end of the acetabular sourcil (AIS and CEAS). The treatment outcome was classified as satisfactory (Severin Grade I or II) or unsatisfactory (Grade III or IV). The intraclass correlation coefficient (ICC) was used to compare the intraobserver and interobserver reliability of each method. We compared the predictability of residual hip dysplasia of each method at 3 years old as a proxy using the area under the receiver operating characteristic (AUC) curve. To evaluate longitudinal change in the acetabular edge's shape, we compared the proportion of hips showing coincidence of the two landmarks between 3 years old and the latest follow-up examination. To investigate whether the longitudinal change in the acetabular edge's shape differs among hips with DDH, contralateral hips, and control hips, we compared the proportion of coincidence among the three groups at both timepoints. RESULTS: Intraobserver and interobserver reliabilities were higher for the CEAB (ICC 0.96; 95% CI, 0.94-0.98 and ICC 0.88; 95% CI, 0.81-0.92, respectively) than for the CEAS (ICC 0.81; 95% CI, 0.70-0.88 and ICC 0.69; 95% CI, 0.55-0.79, respectively). The AIB (AUC 0.88; 95% CI, 0.80-0.96) and CEAB (AUC 0.841; 95% CI, 0.748-0.933) predicted residual hip dysplasia better than the AIS (AUC 0.776; 95% CI, 0.67-0.88) and CEAS (AUC 0.72; 95% CI, 0.59-0.84) (p = 0.03 and p = 0.01, respectively). The proportion of hips showing coincidence of the two landmarks increased from 3 years old to the latest follow-up examination in hips with DDH (37% [25 of 67] to 81% [54 of 67]; OR = 8.8 [95% CI, 3.1-33.9]; p < 0.001), contralateral hips (42% [28 of 67] to 85% [57 of 67]; OR = 16.5 [95% CI, 4.2-141.9]; p < 0.001), and control hips (38% [10 of 26] to 88% [23 of 26]; OR = 14 [95% CI, 2.1-592.0]; p = 0.001). The proportion of coincidence in hips with DDH was not different from that in the contralateral hips and control hips at both timepoints. CONCLUSIONS: Measuring the acetabular index and center-edge angle at 3 years old using the lateral osseous margin of the acetabular roof has higher reliability for predicting residual hip dysplasia than that using the lateral end of the acetabular sourcil in patients with DDH treated with closed reduction. Measuring the acetabular index and center-edge angle at an early age using the lateral end of the sourcil may lead to overdiagnosis of residual hip dysplasia and unnecessary treatment. LEVEL OF EVIDENCE: Level III, diagnostic study.

Overgrowth of the lower limb after treatment of developmental dysplasia of the hip: incidence and risk factors in 101 children with a mean follow-up of 15 years.

Background and purpose - There are few studies on overgrowth of the affected limb after treatment of developmental dysplasia of the hip (DDH). We investigated the incidence of overgrowth and its risk factors in DDH patients.Patients and methods - 101 patients were included in this study. Overgrowth was defined by 2 criteria: when the height of the femoral head of the affected side was higher than that of the contralateral side by more than 10 mm, or by more than 15 mm. The potential risk factors of distinct overgrowth were retrospectively examined using multivariable analysis.Results - When overgrowth was defined as femoral head height difference (FHHD) > 10 mm, its incidence was 44%, and only femoral osteotomy was identified as a significant risk factor with a relative risk (RR) of 1.6 (95% confidence interval [CI] 1.0-2.5). When overgrowth was defined as FHHD > 15 mm, its incidence was 23%, and femoral osteotomy was identified as the only significant risk factor with an RR of 2.3 (CI 1.2-4.5). Overgrowth developed more frequently in patients who underwent femoral osteotomy at the age of 2 to 4 years (87%) than in the others (46%) (p = 0.04).Interpretation - Overgrowth of the affected limb is common in DDH patients. Patients who underwent femoral osteotomy, especially at the age of 2 to 4 years, may require careful follow-up because of the substantial risk for overgrowth.

BGN Mutations in X-Linked Spondyloepimetaphyseal Dysplasia.

Spondyloepimetaphyseal dysplasias (SEMDs) comprise a heterogeneous group of autosomal-dominant and autosomal-recessive disorders. An apparent X-linked recessive (XLR) form of SEMD in a single Italian family was previously reported. We have been able to restudy this family together with a second family from Korea by segregating a severe SEMD in an X-linked pattern. Exome sequencing showed missense mutations in BGN c.439A>G (p.Lys147Glu) in the Korean family and c.776G>T (p.Gly259Val) in the Italian family; the c.439A>G (p.Lys147Glu) mutation was also identified in a further simplex SEMD case from India. Biglycan is an extracellular matrix proteoglycan that can bind transforming growth factor beta (TGF-ß) and thus regulate its free concentration. In 3-dimensional simulation, both altered residues localized to the concave arc of leucine-rich repeat domains of biglycan that interact with TGF-ß. The observation of recurrent BGN mutations in XLR SEMD individuals from different ethnic backgrounds allows us to define "XLR SEMD, BGN type" as a nosologic entity.

Mutations in MAP3K7 that Alter the Activity of the TAK1 Signaling Complex Cause Frontometaphyseal Dysplasia.

Frontometaphyseal dysplasia (FMD) is a progressive sclerosing skeletal dysplasia affecting the long bones and skull. The cause of FMD in some individuals is gain-of-function mutations in FLNA, although how these mutations result in a hyperostotic phenotype remains unknown. Approximately one half of individuals with FMD have no identified mutation in FLNA and are phenotypically very similar to individuals with FLNA mutations, except for an increased tendency to form keloid scars. Using whole-exome sequencing and targeted Sanger sequencing in 19 FMD-affected individuals with no identifiable FLNA mutation, we identified mutations in two genes-MAP3K7, encoding transforming growth factor ß (TGF-ß)-activated kinase (TAK1), and TAB2, encoding TAK1-associated binding protein 2 (TAB2). Four mutations were found in MAP3K7, including one highly recurrent (n = 15) de novo mutation (c.1454C>T [ p.Pro485Leu]) proximal to the coiled-coil domain of TAK1 and three missense mutations affecting the kinase domain (c.208G>C [p.Glu70Gln], c.299T>A [p.Val100Glu], and c.502G>C [p.Gly168Arg]). Notably, the subjects with the latter three mutations had a milder FMD phenotype. An additional de novo mutation was found in TAB2 (c.1705G>A, p.Glu569Lys). The recurrent mutation does not destabilize TAK1, or impair its ability to homodimerize or bind TAB2, but it does increase TAK1 autophosphorylation and alter the activity of more than one signaling pathway regulated by the TAK1 kinase complex. These findings show that dysregulation of the TAK1 complex produces a close phenocopy of FMD caused by FLNA mutations. Furthermore, they suggest that the pathogenesis of some of the filaminopathies caused by FLNA mutations might be mediated by misregulation of signaling coordinated through the TAK1 signaling complex.

Best practice guidelines regarding diagnosis and management of patients with type II collagen disorders.

PURPOSE: Skeletal dysplasias comprise a heterogeneous group of inherited disorders of development, growth, and maintenance of the human skeleton. Because of their relative rarity and wide phenotypic variability, patients should be accurately identified, uniformly assessed, and managed by clinicians who are aware of their potential complications and possess the knowledge and resources to treat them effectively. This study presents expert guidelines developed to improve the diagnosis and management of patients with type II collagen skeletal disorders to optimize clinical outcomes. METHODS: A panel of 11 multidisciplinary international experts in the field of skeletal dysplasia participated in a Delphi process, which comprised analysis of a thorough literature review with subsequent generation of 26 diagnosis and care recommendations, followed by two rounds of anonymous voting with an intervening face-to-face meeting. Those recommendations with more than 80% agreement were considered as consensual. RESULTS: After the first voting round, consensus was reached to support 12 of 26 (46%) statements. After the panel discussion, the group reached consensus on 22 of 24 revised statements (92%). CONCLUSIONS: Consensus-based, expert best practice guidelines developed as a standard of care to assist accurate diagnosis, minimize associated health risks, and improve clinical outcomes for patients with type II collagen skeletal dysplasias.

Novel loss-of-function variants of TRAPPC2 manifesting X-linked spondyloepiphyseal dysplasia tarda: report of two cases.

BACKGROUND: X-linked spondyloepiphyseal dysplasia tarda (SEDT-XL) is a skeletal disorder characterized by defective structures of vertebral bodies and/or of epiphyses of the long bones, resulting in moderately short stature and early joint degeneration. TRAPPC2 gene, which is important for collagen secretion, has been reported as causative for SEDT-XL. CASE PRESENTATION: Here, we report two variants of TRAPPC2 gene of SEDT-XL patients, a missense variant of start codon, c.1A > T, and a deletion variant, c.40delG. To understand molecular consequence of the variants, we establish an in vitro gene expression assay system and demonstrate that both mutated genes are transcribed, but are not properly translated, indicative of the pathogenic nature of those TRAPPC2 variants. CONCLUSIONS: In the current study, we provide additional experimental data showing that loss-of-function TRAPPC2 variants are probably causative for SEDT-XL phenotype. These findings further contribute to the understanding the clinical picture related to TRAPPC2 gene.

Special considerations for clinical trials in fibrodysplasia ossificans progressiva (FOP).

Clinical trials for orphan diseases are critical for developing effective therapies. One such condition, fibrodysplasia ossificans progressiva (FOP; MIM#135100), is characterized by progressive heterotopic ossification (HO) that leads to severe disability. Individuals with FOP are extremely sensitive to even minor traumatic events. There has been substantial recent interest in clinical trials for novel and urgently-needed treatments for FOP. The International Clinical Council on FOP (ICC) was established in 2016 to provide consolidated and coordinated advice on the best practices for clinical care and clinical research for individuals who suffer from FOP. The Clinical Trials Committee of the ICC developed a focused list of key considerations that encompass the specific and unique needs of the FOP community - considerations that are endorsed by the entire ICC. These considerations complement established protocols for developing and executing robust clinical trials by providing a foundation for helping to ensure the safety of subjects with FOP in clinical research trials.

Mycobacterium bovis Osteitis Following Immunization with Bacille Calmette-Guérin (BCG) in Korea.

BACKGROUND: Mycobacterium bovis Bacille Calmette-Guérin (BCG) osteitis, a rare complication of BCG vaccination, has not been well investigated in Korea. This study aimed to evaluate the clinical characteristics of BCG osteitis during the recent 10 years in Korea. METHODS: Children diagnosed with BCG osteitis at the Seoul National University Children's Hospital from January 2007 to March 2018 were included. M. bovis BCG was confirmed by multiplex polymerase chain reaction (PCR) in the affected bone. BCG immunization status and clinical information were reviewed retrospectively. RESULTS: Twenty-one patients were diagnosed with BCG osteitis and their median symptom onset from BCG vaccination was 13.8 months (range, 6.0-32.5). Sixteen children (76.2%) received Tokyo-172 vaccine by percutaneous multiple puncture method, while four (19.0%) and one (4.8%) received intradermal Tokyo-172 and Danish strain, respectively. Common presenting symptoms were swelling (76.2%), limited movement of the affected site (63.2%), and pain (61.9%) while fever was only accompanied in 19.0%. Femur (33.3%) and the tarsal bones (23.8%) were the most frequently involved sites; and demarcated osteolytic lesions (63.1%) and cortical breakages (42.1%) were observed on plain radiographs. Surgical drainage was performed in 90.5%, and 33.3% of them required repeated surgical interventions due to persistent symptoms. Antituberculosis medications were administered for a median duration of 12 months (range, 12-31). Most patients recovered without evident sequelae. CONCLUSION: Highly suspecting BCG osteitis based on clinical manifestations is important for prompt management. A comprehensive national surveillance system is needed to understand the exact incidence of serious adverse reactions following BCG vaccination and establish safe vaccination policy in Korea.

Physeal and Subphyseal Distraction Osteogenesis in Atrophic-type Congenital Pseudarthrosis of the Tibia: Efficacy and Safety.

PURPOSE: To examine the efficacy, safety, and clinical outcomes of distraction osteogenesis through the physis (PDO) or through subphyseal osteotomy (SPDO) in patients with atrophic-type congenital pseudarthrosis of tibia with proximal tibial dysplasia. METHODS: To validate the efficacy and safety of PDO and SPDO, radiographic and clinical parameters were compared between 5 patients who underwent proximal tibial metaphyseal or metadiaphyseal lengthening as a control (group 1) and 7 patients who underwent PDO or SPDO (group 2). Postoperative complication was also compared between the groups. RESULTS: A significant difference in terms of healing index (group 1, 83.3±24.7 d/cm; group 2, 35.0±11.1 d/cm; P=0.001) and percentage increase (11.0%±3.7% vs. 23.1%±10.5%, P=0.034) was observed between the 2 groups. According to the Paley classification, group 1 included 1 "problems" case and 3 "obstacles" cases, whereas group 2 included 2 "problems" cases and 1 "obstacles" case. According to the Lascombes classification, group 1 included 2 grade IIIb cases and 3 grade IV cases, whereas group 2 included 6 grade I cases and 1 grade IIa case. Severe complications were significantly higher in group 1 compared with the group 2 (P=0.007). CONCLUSIONS: This study demonstrated that PDO or SPDO can be effectively and safely performed for tibial lengthening in atrophic-type congenital pseudarthrosis of tibia patients with proximal tibial dysplasia. LEVEL OF EVIDENCE: Level III.

In Vivo Response of Growth Plate to Biodegradable Mg-Ca-Zn Alloys Depending on the Surface Modification.

Because Mg-Ca-Zn alloys are biodegradable and obviate secondary implant removal, they are especially beneficial for pediatric patients. We examined the degradation performance of Mg-Ca-Zn alloys depending on the surface modification and investigated the in vivo effects on the growth plate in a skeletally immature rabbit model. Either plasma electrolyte oxidation (PEO)-coated (n = 18) or non-coated (n = 18) Mg-Ca-Zn alloy was inserted at the distal femoral physis. We measured the degradation performance and femoral segment lengths using micro-CT. In addition, we analyzed the histomorphometric and histopathologic characteristics of the growth plate. Although there were no acute, chronic inflammatory reactions in either group, they differed significantly in the tissue reactions to their degradation performance and physeal responses. Compared to non-coated alloys, PEO-coated alloys degraded significantly slowly with diminished hydrogen gas formation. Depending on the degradation rate, large bone bridge formation and premature physeal arrest occurred primarily in the non-coated group, whereas only a small-sized bone bridge formed in the PEO-coated group. This difference ultimately led to significant shortening of the femoral segment in the non-coated group. This study suggests that optimal degradation could be achieved with PEO-coated Mg-Ca-Zn alloys, making them promising and safe biodegradable materials with no growth plate damage.

Surface Modification of Cisplatin-Complexed Gold Nanoparticles and Its Influence on Colloidal Stability, Drug Loading, and Drug Release.

Cisplatin-complexed gold nanoparticles (PtII-AuNP) provide a promising strategy for chemo-radiation-based anticancer drugs. Effective design of such platforms necessitates reliable assessment of surface engineering on a quantitative basis and its influence on drug payload, stability, and release. In this paper, poly(ethylene glycol) (PEG)-stabilized PtII-AuNP was synthesized as a model antitumor drug platform, where PtII is attached via a carboxyl-terminated dendron ligand. Surface modification by PEG and its influence on drug loading, colloidal stability, and drug release were assessed. Complexation with PtII significantly degrades colloidal stability of the conjugate; however, PEGylation provides substantial improvement of stability in conjunction with an insignificant trade-off in drug loading capacity compared with the non-PEGylated control (<20% decrease in loading capacity). In this context, the effect of varying PEG concentration and molar mass was investigated. On a quantitative basis, the extent of PEGylation was characterized and its influence on dispersion stability and drug load was examined using electrospray differential mobility analysis (ES-DMA) hyphenated with inductively coupled plasma mass spectrometry (ICP-MS) and compared with attenuated total reflectance-FTIR. Using ES-DMA-ICP-MS, AuNP conjugates were size-classified based on their electrical mobility, while PtII loading was simultaneously quantified by determination of Pt mass. Colloidal stability was quantitatively evaluated in biologically relevant media. Finally, the pH-dependent PtII release performance was evaluated. We observed 9% and 16% PtII release at drug loadings of 0.5 and 1.9 PtII/nm2, respectively. The relative molar mass of PEG had no significant influence on PtII uptake or release performance, while PEGylation substantially improved the colloidal stability of the conjugate. Notably, the PtII release over 10 days (examined at 0.5 PtII/nm2 drug loading) remained constant for non-PEGylated, 1K-PEGylated, and 5K-PEGylated conjugates.