The purpose of this study is to explore the pathogenesis and genetic susceptibility of obese subjects,providing a convincing argument for further treatment of obesity and metabolic syndrome.

Obesity has become a major worldwide challenge to public health, owing to an interaction between the obesogenic environment and a strong genetic contribution.Previous studies found that genetic factors determine 40%-70% of obese phenotype.Under such circumstances, the screening of obesity susceptibility gene is particularly important for society or family to take measures to prevent obesity.

Recent extensive genome-wide association studies(GWASs) have identified numerous single nucleotide polymorphisms associated with obesity,but these loci together account for only a small fraction of the known heritable component.Two studies in 2010 Nature,for the first time, put rare copy number variation (CNV)in association with severe early-onset obesity.Their significance lie not only in the discovery of the pathogenic genes of severe early-onset obesity but,more importantly,in providing new strategies for finding out genes that cause complex diseases.

Obese patients and healthy lean controls proved by a series of blood biochemical examinations will be enrolled in this study.The present study intends to use the techniques such as enzyme-linked immunosorbent assay, real-time fluorescence quantitative PCR,gene chip,construction of viral vectors,transfection, taking advantage of the established database,by means of serum assays and functional tests, associate copy number variation with obesity phenotype to explain the root cause of obesity.Meanwhile biomarkers, gut flora and genetic risk factors will be evaluated in the study subjects.

Inclusion Criteria:

• body mass index (BMI)≥ 30kg/m2
• predominantly east China to minimize population stratification
• willing and able to provide informed consent

Exclusion Criteria:

• pregnancy/lactation
• Cushing syndrome
• Hypothyroidism
• obesity caused by pituitary and hypothalamic lesions
• drug related obesity
• history of major psychiatric illness

The population from which cohorts will be selected include students, residents, staff, and/or faculty who are present on Shanghai Jiaotong University school of medicine, and surrounding areas.