多发性骨性连接综合征（SYNS）是一种以全身多发骨关节融合为主要特征的遗传性骨骼系统疾病，多呈常染色体显性遗传。课题组前期在一个庞大的SYNS家系中，利用全外显子组测序技术成功鉴定到GDF6基因杂合错义突变p.Y444N。该突变与家系成员骨融合表征完全共分离，确认GDF6为SYNS新致病基因。GDF6基因属于BMP家族成员，参与骨骼的发育及肌腱的形成，但其具体致病机制不清。本研究拟运用表面等离子共振、鸡胚胎肢芽细胞微团培养和CRISPR/Cas9基因修饰等实验方法，结合体外细胞实验和动物模型研究。评估错义突变p.Y444N对GDF6蛋白表达、与受体和抑制剂结合亲和力及下游信号通路等的影响。研究GDF6及其受体在小鼠胚胎发育过程中的时空表达模式，并观察突变小鼠的病理表型。从而阐明GDF6基因突变p.Y444N导致SYNS的致病机制，并进一步探讨GDF6在骨关节形成、软骨及肌腱发育中的作用。

Multiple synostoses syndrome (SYNS) is a rare autosomal dominant skeletal dysostosis characterized by defects in joint formation and synostoses. In the prior study, we successfully identified a heterozygous mutation (p.Y444N) of GDF6 gene by exome sequencing in a large Chinese pedigree of SYNS. Segregation of this missense mutation in the pedigree members, then the GDF6 gene was confirmed as a novel pathogenic gene in SYNS. GDF6 gene encodes a member of the BMP family, and is required for normal bone development and tendon formation. However, the pathological mechanisms of SYNS is still unclear. This study intends to use the technologies of Western blot, surface plasmon resonance, chicken micromass cultures and CRISPR/Cas9 gene editing etc., uniting the results from in vitro experiments and in vivo animal models. We'd like to assess the the potential pathogenicity of GDF6 missense mutations (p.Y444N), including protein expression, receptor and inhibitors binding affinity, and downstream signaling pathways. We'd also like to study the expression patterns of GDF6 and receptor in mouse embryonic development, and observe the pathological phenotype of the mutant mouse. The purpose of our planed study is to clarify the pathogenic mechanisms of the mutation p.Y444N leading to SYNS, and to further explore the role of GDF6 gene in the formation of bone and joint, and in the development of cartilage and tendon.