Towards complete and error-free genome assemblies of all vertebrate species.

High-quality and complete reference genome assemblies are fundamental for the application of genomics to biology, disease, and biodiversity conservation. However, such assemblies are available for only a few non-microbial species1-4. To address this issue, the international Genome 10K (G10K) consortium5,6 has worked over a five-year period to evaluate and develop cost-effective methods for assembling highly accurate and nearly complete reference genomes. Here we present lessons learned from generating assemblies for 16 species that represent six major vertebrate lineages. We confirm that long-read sequencing technologies are essential for maximizing genome quality, and that unresolved complex repeats and haplotype heterozygosity are major sources of assembly error when not handled correctly. Our assemblies correct substantial errors, add missing sequence in some of the best historical reference genomes, and reveal biological discoveries. These include the identification of many false gene duplications, increases in gene sizes, chromosome rearrangements that are specific to lineages, a repeated independent chromosome breakpoint in bat genomes, and a canonical GC-rich pattern in protein-coding genes and their regulatory regions. Adopting these lessons, we have embarked on the Vertebrate Genomes Project (VGP), an international effort to generate high-quality, complete reference genomes for all of the roughly 70,000 extant vertebrate species and to help to enable a new era of discovery across the life sciences.

Dense sampling of bird diversity increases power of comparative genomics.

Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity1-4. Sparse taxon sampling has previously been proposed to confound phylogenetic inference5, and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families-including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species.

Coincidence measurements of photodouble ionization of benzene and thiophene.

Photodouble ionization (PDI) triple-differential cross sections (TDCSs) of benzene and thiophene have been measured in electron-electron coincidence experiments under 10-10 eV and 20-20 eV equal energy sharing conditions. A multi-Gaussian fit method has been employed to characterize the TDCSs. The trends and features observed for benzene and thiophene do highlight differences with helium most likely from molecular PDI contributions to the TDCS. A comparison with the well-known helium PDI TDCS for equal energy sharing conditions [Avaldi and Huetz J. Phys. B: At. Mol. Opt. Phys., 2005, 38, S861-S891] supported the validity of the multi-Gaussian fitting method and contextualized the benzene and thiophene fits. The molecular targets and energy sharing conditions were chosen to provide insight into the unexpected resonances observed in aromatic hydrocarbons but not aromatic heterocyclic molecules [Wehlitz et al., Phys. Rev. Lett., 2012, 109, 193001]. Contrary to the work of [Wehlitz et al., Phys. Rev. Lett., 2012, 109, 193001], no significant differences between benzene and thiophene were found.

Hip Displacement in Spinal Muscular Atrophy: The Influences of Genetic Severity, Functional Level, and Disease-modifying Treatments.

PURPOSE: Hip displacement (HD) is common in spinal muscular atrophy (SMA), but neither genetic severity nor gross motor function level have been investigated as risk factors. Although disease-modifying agents (DMA) have improved function and overall health, their effects on the prevention of HD are unknown. The purpose of this study was to determine risk factors for HD development in SMA. METHODS: Retrospective cohort. Children with SMA presenting between January 2005 and August 2021, at least 1 hip radiograph, and a minimum 2-year follow-up were included. The primary outcome measure was the prevalence of HD (migration percentage ≥40%). Secondary outcomes included SMA type (I/II/III), survival motor neuron 2 copy number, Hammersmith Functional Motor Scale (HFMS, out of 66), ambulatory status (Functional Mobility Scale at 50 m), clinically relevant scoliosis (>40 degrees and/or surgery), and DMA treatment (>1-year duration, nusinersen/risdiplam/onasemnogene abeparvovec) as risk factors. Univariate and multivariate logistic regression analyses were performed. RESULTS: Eighty-two patients (52% female) with SMA type I (n=32, 39%), II (n=36, 44%), and III (n=14, 17%) met the inclusion criteria, with a final follow-up of 4.5 (SD: 2.7) years. Age at first hip radiograph was 3.4 (SD: 2.9) years. The prevalence of HD was 75.6%, with a mean age of onset of 4.6 (SD: 2.7) years. When stratified by SMA type, the prevalence/age of onset (mean, years) was 84%/3.1 (SD: 1.7), 80%/5.8 (SD: 2.3), and 36%/9.0 (SD: 4.3), respectively. HFMS score >23 was protective against HD by receiver operating characteristic analysis ( P =0.008). Significant risk factors by univariate analysis were SMA type I ( P =0.002) and II ( P =0.002), HFMS ≤23 ( P =0.01), nonambulatory status (Functional Mobility Scale at 50 m = 1, P =0.001), clinically relevant scoliosis ( P =0.01), and DMA treatment ( P =0.01). By multivariate analysis, only SMA type II ( P =0.04) and scoliosis ( P =0.04) were independent risk factors. CONCLUSIONS: The prevalence of HD in SMA is highly linked to disease severity. Identified risk factors can be used in the development of surveillance programs for early detection of HD in SMA, allowing for timely management. LEVEL OF EVIDENCE: Level III.

Scoliosis Development in Spinal Muscular Atrophy: The Influences of Genetic Severity, Functional Level, and Disease-Modifying Treatments.

BACKGROUND: Spinal muscular atrophy (SMA) is caused by abnormalities of the survival motor neuron (SMN) 1 gene, leading to deficiency in SMN protein and loss of spinal cord alpha motor neurons. Newer disease-modifying agents (DMA) targeting the involved genes, including nusinersen and gene replacement therapies, have improved gross motor and respiratory function, but their impact on scoliosis development has not been established. This study aimed to determine risk factors for scoliosis development in SMA, specifically genetic severity and DMA use. METHODS: In this retrospective cohort study, children with SMA and minimum 2-year follow-up were included. The primary outcome was the prevalence of clinically relevant scoliosis. Secondary outcomes included SMA type, SMN2 copy number, Hammersmith Functional Motor Scale (HFMS), ambulatory status [functional mobility scale at 50m (FMS50)], DMA use, and hip displacement as risk factors. Univariate/multivariate logistic regression analyses were performed to identify dependent/independent risk factors. RESULTS: One hundred sixty-five patients (51% female) with SMA types I-III met the inclusion criteria, with total follow-up of 9.8 years. The prevalence of scoliosis was 79%; age of onset 7.9 years. The major curve angle for the entire cohort at first assessment and final follow-up was 37 degrees (SD: 27 degrees) and 62 degrees (SD: 31 degrees) (P<0.0001), respectively. Significant risk factors for scoliosis by univariate analysis were SMA type (I/II, P=0.02), HFMS (>23, P<0.001), nonambulatory status (FMS50=1, P<0.0001), DMA treatment (P=0.02), and hip displacement (P<0.0001). Multivariate analysis revealed that HFMS >23 (P=0.02) and DMA (P=0.05) treatment were independent (protective) risk factors. CONCLUSIONS: The development of scoliosis in SMA is high, with risk factors associated with proxy measures of disease severity, including SMA type, nonambulatory status, hip displacement, and most notably, gross motor function (by HFMS). DMA use and HFMS >23 were associated with a decreased risk of scoliosis development. Identified risk factors can be used in the development of surveillance programs for early detection of scoliosis in SMA. LEVEL OF EVIDENCE: Level III.

Does intrathecal baclofen therapy decrease the progression of hip displacement in young patients with cerebral palsy?

AIM: To evaluate the effects of intrathecal baclofen pump (ITBP) therapy on hip dysplasia in young patients with cerebral palsy (CP). METHOD: This was a retrospective cohort series of prospectively collected data. Inclusion criteria were all patients with CP in Gross Motor Function Classification System (GMFCS) levels IV or V who underwent ITBP placement under 8 years old with at least 5 years of follow-up. Thirty-four patients were matched to a control group of 71 patients based on GMFCS level, motor type, medical comorbidities, worst hip migration percentage at ITBP placement, age, and Modified Ashworth scale scores. Patients were followed for at least 5 years or until they had hip reconstructive surgery. The primary outcome was the development of hip displacement as measured by the migration percentage at the latest follow-up or the preoperative migration percentage before hip reconstruction. RESULTS: The migration percentage at last follow-up was not statistically different between groups (ITBP: 36.2%, non-ITBP: 44.4%, p = 0.14). The rates of future preventative, reconstructive, and recurrent hip surgery were not different between groups. INTERPRETATION: The use of ITBP as an early treatment of spasticity did not alter the natural history of progressive hip displacement in non-ambulatory patients with CP and hip displacement is likely multifactorial, not solely due to spasticity.

Collagenase treatment decreases muscle stiffness in cerebral palsy: A preclinical ex vivo biomechanical analysis of hip adductor muscle fiber bundles.

AIM: To determine the dose-response relationship of collagenase Clostridium histolyticum (CCH) on collagen content and the change in muscle fiber bundle stiffness after ex vivo treatment of adductor longus biopsies with CCH in children with cerebral palsy (CP). METHOD: Biopsy samples of adductor longus from children with CP (classified in Gross Motor Function Classification System levels IV and V) were treated with 0 U/mL, 200 U/mL, 350 U/mL, or 500 U/mL CCH; percentage collagen reduction was measured to determine the dose-response. Peak and steady-state stresses were determined at 1%, 2.5%, 5%, and 7.5% strain increments; Young's modulus was calculated. RESULTS: Eleven patients were enrolled (nine males, two females, mean age at surgery 6 years 5 months; range: 2-16 years). A linear CCH dose-response relationship was determined. Peak and steady-state stress generation increased linearly at 5.9/2.3mN/mm2 , 12.4/5.3mN/mm2 , 22.2/9.7mN/mm2 , and 33.3/15.5mN/mm2 at each percentage strain increment respectively. After CCH treatment, peak and steady-state stress generation decreased to 3.2/1.2mN/mm2 , 6.5/2.9mN/mm2 , 12.2/5.7mN/mm2 , and 15.4/7.7mN/mm2 respectively (p < 0.004). Young's modulus decreased from 205 kPa to 100 kPa after CCH (p = 0.003). INTERPRETATION: This preclinical ex vivo study provides proof of concept for the use of collagenase to decrease muscle stiffness in individuals with CP.

Femoral Head Deformity Associated With Hip Displacement in Nonambulatory Cerebral Palsy: Results at Skeletal Maturity.

BACKGROUND: Maintaining femoral head shape (FHS) and acetabular sphericity are important goals in preventing long-term osteoarthritis in hips in children with cerebral palsy (CP). As acetabular morphology has been widely studied, our objective was to determine FHS in CP after triradiate cartilage (TRC) closure, a proxy for skeletal maturity, and the risk factors associated with residual deformity and osteoarthritis. METHODS: In this retrospective cohort study, patients with CP [Gross Motor Function Classification System (GMFCS) IV to V], minimum 4 yearly hip radiographs after age 10 years, and at least 1 radiograph after age 16 years, were included. Primary outcome was FHS (Rutz), stratified as "less severe" (Rutz A to B) and "more severe" (Rutz C to D). Secondary outcomes included migration percentage (MP), age at TRC closure, previous reconstructive (femoral with/without pelvic osteotomies) surgery, previous intrathecal baclofen, Tönnis osteoarthritis grade, and GMFCS level. Statistical analyses included χ 2 analysis and multiple logistic regression. RESULTS: One hundred sixty-three patients (326 hips) met the inclusion criteria, with TRC closure at age 14.0 (SD: 1.8) years. At final follow-up of 4.4 (SD: 2.4) years after TRC closure, 17% (55 hips), had a "more severe" FHS. From TRC closure to final follow-up, the frequencies of "less severe" hips decreased (-10%, P <0.001), while "more severe" increased (+115%, P <0.001). In multiple regression analysis, MP at TRC closure was the only significant risk factor associated with a "more severe" FHS at final follow-up ( P =0.03). Receiver operating characteristic curve analysis determined MP≥30.5% to be associated with a "more severe" FHS at final follow-up ( P <0.009). The FHS was not affected by reconstructive surgery, sex, GMFCS level, or intrathecal baclofen use. "Less severe" hips had lower Tönnis grades (0 to 1) compared with "more severe" hips (Tönnis grades 2 to 3) at final follow-up ( P <0.001). CONCLUSIONS: FHS at skeletal maturity was not influenced by prior reconstructive surgery but was negatively affected when MP≥30.5% at the time of TRC closure. The extent of residual femoral head deformity correlated with the severity of osteoarthritis at final follow-up. LEVEL OF EVIDENCE: Level III.

Hip Displacement Does Not Change After Pelvic Obliquity Correction During Spinal Fusion in Children With Cerebral Palsy.

BACKGROUND: Children with cerebral palsy (CP) frequently develop both neuromuscular hip dysplasia and scoliosis, and occasionally, the timing of the worsening of both of these pathologies is concurrent. The question as to whether the hip or spine should be addressed first in CP remains controversial, with the majority of evidence being "expert opinion." The purpose of this project was to determine the impact of posterior spinal fusion (PSF) on the change in hip displacement for children with CP without previous reconstructive hip surgery. METHODS: This was an Institutional Review Board-approved study that observed 67 patients from 2004 to 2018. Inclusion criteria included children with CP, 18 years of age and younger, Gross Motor Function Classification System IV and V, undergoing PSF at a single tertiary care children's hospital with a minimum 2-year follow-up. The primary outcome was the change in hip displacement as quantified by the migration percentage (MP). The hip with the highest MP (worst hip) at the spine preoperative analysis were included for analysis. Triradiate cartilage (TRC) status and pelvic obliquity correction were analyzed with multivariate analysis. RESULTS: Sixty-seven patients were included for analysis, with a mean age of 12.5±2.3 years. The mean major curve angle of the major curve was 77±23 degrees and the mean preoperative pelvic obliquity was 21±12 degrees. There was no statistically significant change in MP after PSF from a mean preoperative value of 41±27%, to a mean postoperative value of 41±29% at the last follow-up, (P=0.76) The mean follow-up time was 4.1±2.7 years. TRC status (P=0.52) and the severity of pelvic obliquity (P=0.10) did not statistically impact the change in MP after PSF. CONCLUSION: PSF did not influence-either negatively or positively-the progression of hip displacement in children with CP, regardless of pelvic obliquity correction or TRC status. The lack of deterioration in hip displacement post-PSF, however, may suggest a protective effect of spine surgery. LEVEL OF EVIDENCE: Level III-retrospective cohort study.

Is Standing Function Improved After Orthopaedic Surgery in Children With Cerebral Palsy at GMFCS Levels III/IV?

BACKGROUND: Children with cerebral palsy (CP) at Gross Motor Function Classification System (GMFCS) levels III/IV are at risk for losses in standing function during adolescence and transition to adulthood. Multilevel surgery (MLS) is an effective treatment to improve gait, but its effects on standing function are not well documented. The objectives of our study were to describe standing function in children with CP classified as GMFCS levels III/IV and evaluate change after MLS. METHODS: This retrospective study included children with CP (GMFCS III/IV) ages 6 to 20 years who underwent instrumented gait analysis. A subset who underwent MLS were evaluated for change. Primary outcome measures were Gross Motor Function Measure dimension D, gait velocity, functional mobility scale, and the Pediatric Outcomes Data Collection Instrument (PODCI). Additional impairment level measures included foot pressure, knee extension during stance phase of gait, and knee extension passive range of motion. RESULTS: Four hundred thirty-seven instrumented gait analysis sessions from 321 children with CP (ages 13.7±4.8 y; GMFCS III-81%/IV-19%) were included. The GMFCS III group had higher Gross Motor Function Measure dimension D, gait velocity, PODCI scores, and better knee extension compared with the GMFCS IV group ( P <0.05); 94 MLS were evaluated for postoperative change 15.3±4.2 months after MLS. Children at GMFCS level III had improved PODCI scores ( P <0.05), better knee extension passive range of motion ( P <0.01), and improved coronal plane foot pressure ( P <0.05) post MLS. Maximum knee extension during stance and heel impulse improved significantly in both groups ( P <0.01). CONCLUSIONS: Standing function of children with CP at GMFCS IV was significantly more limited than at GMFCS III. After MLS, both groups (III/IV) showed improvement in impairment level outcomes (knee extension and foot position), whereas only those functioning at GMFCS III had improvement in activity/participation outcomes according to the PODCI. For children with CP at GMFCS levels IV, MLS may improve standing function, but appropriate goals related to assisted standing and measurement protocols sensitive to limited functional mobility should be adopted. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Understanding skeletal muscle in cerebral palsy: a path to personalized medicine?

Until recently, there has been little interest in understanding the intrinsic features associated with the pathomorphology of skeletal muscle in cerebral palsy (CP). Coupled with emerging evidence that challenges the role of spasticity as a determinant of gross motor function and in the development of fixed muscle contractures, it has become increasingly important to further elucidate the underlying mechanisms responsible for muscle alterations in CP. This knowledge can help clinicians to understand and apply treatment modalities that take these aspects into account. Thus, the inherent heterogeneity of the CP phenotype allows for the potential of personalized medicine through the understanding of muscle pathomorphology on an individual basis and tailoring treatment approaches accordingly. This review aims to summarize recent developments in the understanding of CP muscle and their relationship to musculoskeletal manifestations, in addition to proposing a treatment paradigm that incorporates this new knowledge.

Walking activity after multilevel orthopedic surgery in children with cerebral palsy.

AIM: To determine how surgical burden and preoperative factors affect the recovery of walking activity after multilevel orthopedic surgery (MLS). METHOD: In this retrospective study, inclusion criteria were a diagnosis of cerebral palsy, MLS, and walking activity monitoring using a StepWatch device within 12 months pre-MLS and 24 months post-MLS. The outcome measure was total mean strides per day normalized to age and Gross Motor Function Classification System level. Pre- and postoperative walking activity were compared using unpaired t-tests; the effects of preoperative predictors and surgical burden on the recovery of walking activity were evaluated using regression analysis. RESULTS: Participants included 178 children (mean age 12 years 10 months [SD 8 years 7 months; range 4-20 years]; 91 males, 87 females). On average, children returned to baseline walking activity 3 months after low-burden surgery and 1 year 2 months after high-burden surgery. Postoperative walking activity was higher for children who had surgery at a younger age and those with a higher preoperative mobility function. INTERPRETATION: The burden of MLS was found to be inversely related to the time to recovery of postoperative walking activity. These findings provide evidence to help clinicians set expectations for return to function post-MLS. Further study is necessary to investigate the impact of postoperative factors on walking activity recovery. WHAT THIS PAPER ADDS: High-burden surgeries lead to longer recovery than low-burden surgeries. Younger children recover walking activity faster after multilevel orthopedic surgery. Children with high preoperative mobility function recover walking activity faster after surgery.

OBJETIVO: Determinar como a carga cirúrgica e os fatores pré-operatórios afetam a recuperação da atividade de caminhada após cirurgia ortopédica multinível (MLS). MÉTODOS: Neste estudo retrospectivo, os critérios de inclusão foram um diagnóstico de paralisia cerebral, MLS e monitoramento da atividade de caminhada usando um dispositivo Step Watch dentro de 12 meses pré-MLS e 24 meses pós-MLS. A medida de resultado foi o total de passos médios por dia normalizados para idade e nível do Sistema de Classificação da Função Motora Grossa. A atividade de caminhada pré e pós-operatória foi comparada usando testes t não pareados; os efeitos dos preditores pré-operatórios e da carga cirúrgica na recuperação da atividade de caminhada foram avaliados por meio de análise de regressão. RESULTADOS: Os participantes incluíram 178 crianças (idade média de 12 anos e 10 meses [DP 8 anos e 7 meses; intervalo de 4 a 20 anos]; 91 meninos, 87 meninas). Em média, as crianças retornaram à atividade de caminhada inicial 3 meses após a cirurgia de baixa carga e 1 ano e 2 meses após a cirurgia de alta carga. A atividade de caminhada pós-operatória foi maior para crianças que foram operadas em idade mais jovem e aquelas com maior função de mobilidade pré-operatória. INTERPRETAÇÃO: A carga de MLS foi inversamente relacionada ao tempo de recuperação da atividade de caminhada pós-operatória. Esses achados fornecem evidências objetivas para ajudar os médicos a definir as expectativas de retorno à função pós-MLS. Mais estudos são necessários para investigar o impacto dos fatores pós-operatórios na recuperação da atividade de caminhada.

Primary Balloon Angioplasty Versus Hydrostatic Dilation for Arteriovenous Fistula Creation in Patients with Small-Caliber Cephalic Veins: A Systematic Review and Meta-Analysis.

BACKGROUND: For arteriovenous fistula (AVF) presence of a venous segment with adequate diameter is essential which is lacking in many patients. To find the optimal augmentation technique in patients with small-caliber cephalic vein (i.e., cephalic vein diameter <3 mm), studies compared primary balloon angioplasty (PBA) versus hydrostatic dilation (HD); however, it remained debatable. This systematic review seeks to determine which technique is preferable. METHODS: We searched MEDLINE, PubMed, Embase, and Google Scholar. Primary outcomes were 6-month primary patency, reintervention, and working AVF. Secondary outcomes were immediate success, the AVF's maturation time (day), and surgical site infection. RESULTS: Three randomized controlled trials yielding 180 patients were included, of which 89 patients were in the PBA group. The odds ratio (OR) of primary patency was significantly higher in the PBA group (OR 6.09, 95% confidence interval [CI], 2.36-15.76, P = 0.0002), the OR of reintervention was significantly lower in the PBA group (OR 0.16, 95% CI, 0.06-0.42, P = 0.0002), and the OR of working AVF was greater in PBA group (OR 4.22, 95% CI, 1.31-13.59, P = 0.02). The OR of immediate success was significantly greater in the PBA group (OR 11.42, 95% CI, 2.54-51.42, P = 0.002), and the AVF maturation time was significantly shorter in patients who underwent PBA (mean difference -20.32 days, 95% CI, -30.12 to -10.52, P = 0.0001). The certainty of the evidence was high. CONCLUSIONS: PBA of small cephalic veins with diameter ≤2.5 cm is a safe, feasible, and efficacious augmentation method for AVF creation. This technique achieves favorable maturation outcomes, and PBA is superior to the standard hydrostatic dilatation technique.

Prevalence and Risk Factors Associated With Pelvic Rod/Screw Radiographic Lucency Following Scoliosis Surgery in Spastic Cerebral Palsy: A Longitudinal Study.

BACKGROUND: Radiographic lucency around a smooth pelvic rod (Galveston/unit rod technique) or sacroiliac/iliac screw following spinal fusion in children with nonambulatory spastic cerebral palsy (CP) has been described as a "windshield wiper" phenomenon. We evaluated demographics, radiographs, and complications in 101 cases from a single center to determine prevalence, risk factors, and complications associated with persistent radiographic lucency from 1 to 5 years following spinal fusion. METHODS: Inclusion criteria were diagnosis of nonambulatory spastic quadriplegic CP [Gross Motor Function Classification System (GMFCS) IV-V], under 18 years of age, scoliosis treated by posterior fusion from upper thoracic to sacrum with pelvic fixation (Galveston rod, iliac screw, or sacroiliac screw), adequate radiographs (preoperative, immediate postoperative, first-year, and second-year), and minimum 5-year follow-up. We evaluated demographics, radiographic parameters, comorbidities, scoliosis curve type, type of pelvic screw/rod, use of off-set connector, screw width, associated with posterior column osteotomy and/or additional anterior spinal release concurrent with posterior spine fusion, and infection over the follow-up period. Specific attention was given to the area and shape of the radiographic lucency. The logistic regression analysis was performed for continuous and categorical variables to define risk factors ( P =0.05). RESULTS: In 101 patients, data were collected at mean intervals of 1-year, 2-year, and >5-year follow-up and were 12.9±1.5, 25.8±2.5, and 81.5±23.0 months, respectively. Prevalence of pelvic rod/screw radiographic lucency was unchanged at 33%, 35%, and 24% at 1-year, 2-year, and >5-year follow-up, respectively, and radiographic parameters did not change ( P >0.05). Furthermore, no risk factors or complications were associated with radiographic lucency around pelvic rods/screws ( P >0.05). CONCLUSION: In patients with spastic nonambulatory CP who had scoliosis treated with posterior spinal fusion from upper thorax to pelvis, the prevalence of pelvic rod/screw lucency is high. Persistent lucency >2 mm around pelvic implants is not clinically significant, does not warrant advanced imaging, or indicate a complication if stable over time and wider distally than proximally. LEVEL OF EVIDENCE: Level III.

No Difference in the Rates of Unplanned Return to the Operating Room Between Magnetically Controlled Growing Rods and Traditional Growth Friendly Surgery for Children With Cerebral Palsy.

BACKGROUND: Early-onset scoliosis (EOS) is common in children with cerebral palsy (CP). The effectiveness of magnetically controlled growing rods (MCGR) and the risk for unplanned return to the operating room (UPROR) remain to be studied in this patient population. The primary outcome of this study was to examine the frequency of UPROR between MCGRs as compared with traditional growth friendly (TGF) surgeries for children with EOS secondary to CP. METHODS: Patients with EOS secondary to CP were prospectively identified from an international database, with data retrospectively analyzed. Scoliosis, kyphosis, T1-S1, and T1-T12 height were measured preoperation, immediate postoperation, and at minimum 2-year follow-up. The risk and etiology of UPRORs were compared between MCGR and TGF. RESULTS: Of the 120 patients that met inclusion criteria, 86 received TGF (age 7.5±0. 1.8 y; mean follow-up 7.0±2.9 y) and 34 received MCGR (age 7.1±2.2 y, mean follow-up 2.8±0.0.5 y). Compared with TGF, MCGR resulted in significant improvements in maintenance of scoliosis (P=0.007). At final follow-up, UPRORs were 8 of 34 patients (24%) for MCGR and 37 of 86 patients (43%) for TGF (P=0.05). To minimize the influence of follow-up period, UPRORs within the first 2 years postoperation were evaluated: MCGR (7 of 34 patients, 21%) versus TGF (20 of 86 patients, 23%; P=0.75). Within the first 2 years, etiology of UPROR as a percentage of all patients per group were deep infection (13% TGF, 6% MCGR), implant failure/migration (12% TGF, 9% MCGR), dehiscence (4% TGF, 3% MCGR), and superficial infection (4% TGF, 3% MCGR). The most common etiology of UPROR for TGF was deep infection and for MCGR was implant failure/migration. CONCLUSION: For patients with EOS secondary to CP, there was no difference in the risk of UPROR within the first 2 years postoperatively whether treated with TGF surgery or with MCGRs (23% TGF, 21% MCGR). LEVEL OF EVIDENCE: Level III-retrospective cohort, therapeutic study.

Hip Displacement in MECP2 Disorders: Prevalence and Risk Factors.

BACKGROUND: Methyl-CpG binding protein 2 (MECP2) disorders, including Rett syndrome and MECP2 duplication syndrome, are typified by profound intellectual disability, spasticity, and decline in gross motor function. Unlike scoliosis, linked to disease severity, little has been reported regarding the hip. The aim of this study was to report the prevalence and risk factors of hip displacement (HD) in MECP2 disorders. METHODS: This was a retrospective, comparative study. Children with a genetically confirmed MECP2 disorder were included. The primary outcome measure was the prevalence of HD (migration percentage>30%). Secondary outcomes included age at HD onset, ambulatory status, presence of clinically relevant scoliosis, genetic severity, presence of seizures, and associated comorbidities. Analysis of proportions of categorical variables was performed using χ2 testing (P=0.05). RESULTS: Fifty-six patients (54 Rett syndrome and 2 MECP2 duplication syndrome), diagnosed at 6.6 (SD: 4.7) years, met the inclusion criteria. The prevalence of HD was 36% [onset, 7.7 (SD: 3.8) y]. Risk factors for HD were nonwalker status (P=0.04), scoliosis (P=0.001), and refractory epilepsy (P=0.04). CONCLUSIONS: The prevalence of HD in MECP2 disorders is comparable to cerebral palsy, associated with proxy measures of disease severity. These results can be used to develop hip surveillance programs for MECP2 disorders, allowing for timely management. LEVEL OF EVIDENCE: Level III.

Orthopaedic Manifestations of Transverse Myelitis in Children.

BACKGROUND: Transverse myelitis (TM) is a rare inflammatory disorder of the spinal cord. It can have a heterogeneous presentation with sensory, motor, and autonomic dysfunction. Neurological sequelae of TM include autonomic dysfunction, motor weakness, and/or spasticity. Studies describing orthopaedic deformities and treatments associated with TM are nonexistent. This purpose of this study was to describe the orthopaedic manifestations of TM in children. METHODS: A multicenter retrospective review was conducted of patients, 0 to 21 years of age, with TM presenting over a 15-year period at 4 academic children's hospitals. Those with confirmed diagnosis of TM and referred to an orthopaedic surgeon were included. Demographics, orthopaedic manifestations, operative/nonoperative treatments, and complications were recorded. Descriptive statistics were used for data reporting. RESULTS: Of 119 patients identified with TM, 37 saw an orthopaedic surgeon. By etiology, 23 were idiopathic (62%), 10 infectious (27%), 3 (8%) inflammatory/autoimmune, and 1 (3%) vascular. The mean age at diagnosis was 6.7 (SD: 5.5) years and at orthopaedic presentation was 8.4 (SD: 5.2) years. Orthopaedic manifestations included scoliosis in 13 (35%), gait abnormalities in 7 (19%), foot deformities in 7 (19%), upper extremity issues in 7 (19%), symptomatic spasticity in 6 (16%), lower extremity muscle contractures in 6 (16%), fractures in 6 (16%), hip displacement in 3 (8%), pain in 2 (5%), and limb length discrepancy in 2 (5%) patients. Seven children (19%) were seen for establishment of care. In all, 14 (38%) underwent operative intervention, mainly for soft-tissue and scoliosis management. Four patients had baclofen pump placement for spasticity management. Postoperative complications occurred in 36% of cases, most commonly because of infection. Neither topographic pattern nor location of lesion had a significant relationship with need for hip or spine surgery. CONCLUSIONS: This report describes the orthopaedic manifestations associated with TM in children, nearly 40% of whom required operative intervention(s). Understanding the breadth of musculoskeletal burden incurred in TM can help develop surveillance programs to identify and treat these deformities in a timely manner. LEVEL OF EVIDENCE: Level IV.

The genome of a songbird.

The zebra finch is an important model organism in several fields with unique relevance to human neuroscience. Like other songbirds, the zebra finch communicates through learned vocalizations, an ability otherwise documented only in humans and a few other animals and lacking in the chicken-the only bird with a sequenced genome until now. Here we present a structural, functional and comparative analysis of the genome sequence of the zebra finch (Taeniopygia guttata), which is a songbird belonging to the large avian order Passeriformes. We find that the overall structures of the genomes are similar in zebra finch and chicken, but they differ in many intrachromosomal rearrangements, lineage-specific gene family expansions, the number of long-terminal-repeat-based retrotransposons, and mechanisms of sex chromosome dosage compensation. We show that song behaviour engages gene regulatory networks in the zebra finch brain, altering the expression of long non-coding RNAs, microRNAs, transcription factors and their targets. We also show evidence for rapid molecular evolution in the songbird lineage of genes that are regulated during song experience. These results indicate an active involvement of the genome in neural processes underlying vocal communication and identify potential genetic substrates for the evolution and regulation of this behaviour.