Whole Exome Sequencing Identifying Genetic Etiology Of Congenital Scoliosis In Chinese Han Population

Background:Congenital Scoliosis （CS） is a spinal deformity with a spinal coronary curvature of10°or greater caused by abnormal vertebrate development during embryo. CS is charatered by rapid development, severe deformity and multiple complications. It is one of the most causes of adolescent disability and brings high burden to the family and the society.The spine of the vertebrate is developed from the presomitc mesoderm （PSM） from which somite is periodically developed, this process is called somitogenesis. Abnormal somitogenesis is the reason of congenital vertebrate deformity. Somitogenesis is regulated by the mutual cooperation of WNT, NOTCH and FGF signaling pathway and their taget genes. However, the definite etiology of CS is obscure and there is still no effective method for its early prediction. Clinially, the treatment of CS is mainly focused on bracement and operation in order to avoid the rapid progress of the disease. Therefore, it is important to find the etiology and to reduce the occurrence of this high pathogenic spinal deformity.The abnormal of genes and changes of environmental factors in embryo or during labor are the main casue of CS. With more and more genetic etiology were reported, the genetic influence of CS is gradually remarked. CS is a complicated disease with multiple genes and multi genetic models related. Little larege sample of genetics research of CS was reported because it is difficult to collect large scale of patients with the same phenotype as patients are usually infertile, furthermore, the strategy of analysis based on the mouse-human synteny restricts the profound and creative study as the real mechanism of molecular biological etiology of CS is unknow either.With the rapid advancement of the sequencing technique, the coast of sequencing is reducing correspondingly. Up to now, whole exome sequencing （WES） has been the most effective method to locate the genetic cause of diseases. WES is a high-performance method in detecting mutations in exome wide and according to the journal of "Science", WES was chosen as one of the top ten breakthroughs of science in2010. There are hundreds of publications reporting using WES to find the genetics etiology of certain disease. As the importance of WES is realized by more and more researchers and the further decline of the cost of WES, it will be used in more cases especially those complicated ones and more important genetic foundamental knowledge of disease wll be provided. The apperance of WES brings evolution in methodology of genetic research of CS, and it is possible for us to find the pathogenic mutation in the level of exome wide.Objects:To investigate the genetic mutation of CS in whole exome level.Methods:We collected four sporadic cases （CS012/CS039/CS070/CS108） and one trio of CS （CS051/CS052/CS053） in Chinese Han population, the classification was type III clinically and M-SDV-U according to ICVAS. Genomic DNA was draw from the whole peripheral blood. We used whole exome sequencing and construct different models in statistical analysis to identify genetic mutations in these cases.Results:1. No homozygous of compound heterozygou mutation were shared by two or more patients in recessive model.2. One non-synonymous mutation of FAM179B （CS05114₄5475484_A/G） was identified in dominant de novo mutation model, but functionally inexplainable.3. Two non-synonymous mutations of FANCA （CS05116₈9833556_A/G and CS1081689842161_T/A） were identified in two cases. No exome mutation was found in three or more cases.4. After knowledge-based data mining, two candidate mutations, ZIC3（CS070X₁36651147_A/T、CS108X₁36648948_C/T） and TBX6（CS01016₃0100451_G/A）, were identified.Conclusions:1. The strategy of "sporadic cases combined with trio in identifying exome level mutatoins of CS in mutiple models" is a feasible approcah for genetic research of CS.2. The mutation of FANCA （16₈9833556_A/G and16₈9842161_T/A） may be closely related to CS with the model of incomplete penetrance.3. The mutation of ZIC3（X₁36651147_A/T and X₁36648948_C/T） may be the cause of CS especially those associated with neural tube defects and congenital heart malformations.4. The mutation of TBX6（16₃0100451_G/A） may be the cause of CS especially those associated with abnormal ribs.