Haiqing Cai

Effect of Variation of ABCB1 and ABCC3 Genotypes on the Survival of Bone Tumor Cases after Chemotherapy

We conducted a comprehensive study to investigate the role of genes involved in transport pathways in response to chemotherapy and clinical outcome of osteosarcoma cases. Genotyping of six SNPs was performed in a 384-well plate format on the Sequenom MassARRAY platform for 208 osteosarcoma patients to reveal any correlations of the six SNPs with response to chemotherapy and clinical outcome. Individuals with the ABCB1 rs1128503 TT and ABCC3 rs4148416 TT genotypes had a higher probability of responding poorly to chemotherapy, indicated by odds ratios (ORs) of 2.46 (95%CI, 1.21-5.74) and 3.78 (95% CI, 1.20-13.85), respectively. Moreover, the ABCB1 rs1128503 TT and ABCC3 rs4148416 TT genotypes were significantly associated with shorter disease- free survival (DFS) and overall survival (OS). Our study found the two SNPs in two transporter genes and one phase II metabolism enzyme to be associated with response to chemotherapy and overall survival in osteosarcoma patients, suggesting potential prognostic biomarker applications of the two SNPs.

A New Subtype of Multiple‐Synostoses Syndrome is Caused by a Mutation in GDF6 that Decreases its Sensitivity to Noggin and Enhances its Potency as a BMP Signal

Growth and differentiation factors (GDFs) are secreted signaling molecules within the BMP family that have critical roles in joint morphogenesis during skeletal development in mice and humans. Using genetic data obtained from a six‐generation Chinese family, we identified a missense variant in GDF6 (NP_001001557.1; p.Y444N) that fully segregates with a novel autosomal dominant synostoses (SYNS) phenotype, which we designate as SYNS4. Affected individuals display bilateral wrist and ankle deformities at birth and progressive conductive deafness after age 40 years. We find that the Y444N variant affects a highly conserved residue of GDF6 in a region critical for binding of GDF6 to its receptor(s) and to the BMP antagonist NOG, and show that this mutant GDF6 is a more potent stimulator of the canonical BMP signaling pathway compared with wild‐type GDF6. Further, we determine that the enhanced BMP activity exhibited by mutant GDF6 is attributable to resistance to NOG‐mediated antagonism. Collectively, our findings indicate that increased BMP signaling owing to a GDF6 gain‐of‐function mutation is responsible for loss of joint formation and profound functional impairment in patients with SYNS4. More broadly, our study highlights the delicate balance of BMP signaling required for proper joint morphogenesis and reinforces the critical role of BMP signaling in skeletal development.

Three novel missense mutations in the filamin B gene are associated with isolated congenital talipes equinovarus

Congenital talipes equinovarus (CTEV) is one of the most common musculoskeletal disorders. Genetic factors have been suggested to be an important contributor to its pathogenesis. Some genes, including PITX1, TBX4, and RBM10, have been associated with CTEV. We aimed to determine the disease-causing mutations in Chinese patients with isolated CTEV. Genomic DNA was extracted from peripheral blood samples of a three-generation pedigree and 53 sporadic patients with CTEV. Whole-exome sequencing and Sanger sequencing were used to identify and validate disease-causing mutations, respectively. A putative pathogenic mutation c.4717G>T (p.D1573Y) in the filamin B (FLNB) gene, which co-segregated with CETV, was identified in the pedigree. Two additional novel missense mutations in the same gene [c.1897A>G (p.M633V) and c.2195A>G (p.Y732C)] were identified from the 53 sporadic patients. Plasmids expressing wild-type or mutant constructs were transfected into HEK293T cells to determine whether these amino acid substitutions affect protein activity. All three (M633V, Y732C, and D1573Y) affected FLNB protein expression and led to cytoplasmic focal accumulation. Our results provide evidence for the involvement of FLNB in the pathogenesis of isolated CTEV and have expanded the clinical spectrum of FLNB mutations.

Quality of reduction and prognosis of developmental dysplasia of the hip: a retrospective study.

Introduction Using limited MRI we evaluated the quality of closed reduction and prognosis in a group of patients with developmental dysplasia of the hip (DDH). Methods Limited MRI was performed on 28 DDH patients (41 hips) after closed reduction. All the hips were divided into deep and incomplete concentric reduction groups according to the femoral head-acetabular distance (FAD) and the shape of the labrum on limited MRI. The abduction angle of the hips, and the initial and final acetabular index (AI) were measured. Presence or absence of the ossification centre of the femoral head before treatment, the Tönnis classification and avascular necrosis of the femoral head and types (Bucholz and Ogden type) were recorded. The data of the 2 groups were analysed with SPSS software. Results We found no significant differences in age, gender, side, preoperative ossification centre of the femoral head, preoperative AI, decreased postoperative AI and abduction angles of hips between the 2 groups. There were significant statistical differences in the preoperative Tönnis grade, FAD after reduction, AI at the final follow-up, severe residual deformity and severe avascular necrosis of the femoral head (p<0.05). The cure rate showed a significant trend (p = 0.052). Conclusions Limited MRI enables effective determination of the quality of reduction immediately after closed reduction. The prognosis of the deep concentric reduction group was better than the group with incomplete concentric reduction.

Mutational screening of GLI3, SHH, preZRS, and ZRS in 102 Chinese children with nonsyndromic polydactyly

Background: Polydactyly is a group of congenital limb malformations that show high degree of phenotypic variability and genetic heterogeneity. Results: In the present study, four genomic regions (exons of GLI3, SHH, and noncoding sequences of preZRS and ZRS) involved in hedgehog (Hh) signaling pathway were sequenced for 102 unrelated Chinese children with nonsyndromic polydactyly. Two GLI3 variants (c.2844 G > G/A; c.1486C > C/T) and four preZRS variants (chr7:156585336 A>G; chr7:156585421 C>A; chr7: 156585247 G>C; chr7:156585420 A > C) were observed in 2(2.0%) and 6(5.9%) patients, respectively. These variants are not over‐represented in the Chinese healthy population. All the 8 cases showed preaxial polydactyly in hands. Additionally, no specific patterns of malformation predicted mutations in other candidate genes or sequences. Conclusions: This is the first report of the assessment of the frequency of GLI3/SHH/preZRS/ZRS in Chinese patients to show any higher possibility of mutations or variants for the 4 genes or sequences in China. Developmental Dynamics 246:392–402, 2017.

Elastic stable intramedullary nailing for severely displaced distal tibial fractures in children.

AbstractElastic stable intramedullary nailing (ESIN) has became a well-accepted method of osteosynthesis of diaphyseal fractures in the skeletally immature patient for many advantages, the purpose of this study is to evaluate the preliminary results of this minimally invasive treatment for severely displaced distal tibial diaphyseal metaphyseal junction (DTDMJ) fractures.This study was carried out over a 6-year period. Twenty-one severely displaced DTDMJ fractures treated using ESIN were evaluated clinically and radiographically. Complications were assessed: the patients were evaluated with regard to nonunion, malunion, infection, growth arrest, leg length discrepancy, implant irritation, and joint function.Mean age at the time of surgery was 7.8 years (range between 5.3 and 14.8 years), mean body weight 34.1 kg, all fractures were transverse or mild oblique type, including 3 open fractures, 5 multifragmented fractures, and 4 fractures associated with polytrauma; 6 cases were treated with antegrade ESIN of tibia while 15 cases need combined retrograde fibula and antegrade tibia fixation treatments. Follow-ups were ranging from 11 to 36 months, 19 fractures showed both clinical and radiographic evidence of healing within 5 months; all cases had full range motion of knee and ankle with symmetrical foot progress angle. Nail removal was at a mean 7.1 months, at final follow-up, no growth arrest or disturbances occurred. Five patients had complications; leg length discrepancy had decreased yet affected 2 patients, 2 cases showed delayed union, and 1 case developed restricted dorsal extension at the metatarsophalangeal joint of the hallux.ESIN is the treatment of choice for pediatric severely displaced DTDMJ fractures that cannot be reduced by closed reduction or ones that cannot be casted. The advantages include faster fracture healing, excellent functional and cosmetic results, safe and reliable surgical technique, and lower severe complication rate.

A novel missense mutation of TNNI2 in a Chinese family cause distal arthrogryposis type 1.

The distal arthrogryposis (DA) syndromes are a group of disorders characterized by congenital contractures of limbs. According to phenotypical characteristics, DA syndromes have been clinically classified into 10 types. Currently, at least nine disease causing genes have been identified for different types of DA. Here, we report a 3‐generation Chinese pedigree with three DA affected members. We performed whole exome sequencing on two affected and one unaffected individuals of this family and successfully identified a novel missense mutation in TNNI2 as the pathogenic mutation. The TNNI2 gene encodes a subunit of the troponin complex, a contractile machinery of the muscle. The mutation p.F178C that could change the H‐bond formation of a neighboring residue occurs at a highly conserved position, suggesting that this variation probably affects the TNNI2 protein function. Our study also demonstrates the power of whole exome sequencing in causal mutation identification for phenotypically variable and genetically heterogeneous disorders.

Pre-bent elastic stable intramedullary nail fixation for distal radial shaft fractures in children

Objective:  To investigate the functional and radiographic outcomes of pre‐bent elastic stable intramedullary nail in treatment of distal radial shaft fractures in children.

A novel GJA1 mutation identified by whole exome sequencing in a Chinese family with autosomal dominant syndactyly

Abstract Syndactyly is one of the most common hereditary limb malformations characterized by fusion of adjacent fingers and/or toes. The current classification scheme of non-syndromic syndactyly defines at least nine well-characterized syndactylous entities with subdivisions based on phenotype and genotype. Here, we reported a 3-generation Chinese pedigree with four affected Syndactyly members inherited in an autosomal dominant manner. We performed whole exome sequencing on two affected members and successfully identified a novel missense mutation p.R101L in GJA1 as the pathogenic mutation. The manifestations caused by GJA1 R101L mutation are different from typical characteristics of oculodentodigital dysplasia. Connexin 43 (Cx43), encoded by GJA1, plays a key role in normal facial and limb development. Arg101Leu mutation caused a hydrophobic to hydrophilic substitution, changing the structural integrity and stability of the molecule. Three-dimensional structural analysis showed this mutation could alter the conformation of residue side chain and produce steric clashes with spatial adjacent residues and cause folding destabilization, suggesting this amino acid appears to play an important role in the structure and function of Cx43. Our study also demonstrates the power of whole exome sequencing in causal mutation identification for phenotypically variable and genetically heterogeneous disorders.

Risk factors for refracture of the forearm in children treated with elastic stable intramedullary nailing

PurposeThis study aims to investigate risk factors for refracture of the forearm in children treated with elastic stable intramedullary nailing (ESIN).MethodsClinical data of 267 patients who had been treated for forearm fractures by ESIN in our hospital from January 2010 to December 2014 were retrospectively reviewed. Risk factors for forearm refractures were determined using logistic regression analysis.ResultsForearm refractures occurred in 11 children. Univariate analysis revealed that age, body weight, number of fractures, open fracture, nail diameter, and immobilization time were not associated with refractures. However, gender (male, P = 0.042) and fracture location (lower third, P = 0.007) were significantly associated with refractures. Multivariate analysis revealed that fracture location was an independent risk factor for forearm refractures (P = 0.031).ConclusionForearm refracture is uncommon in children treated with ESIN. Fracture location is an independent risk factor for forearm refractures in these patients.