title: Genetic association, mRNA and protein expression analysis identify ATG4C as a susceptibility gene for Kashin-Beck disease.
abstract: Recent study observed defective autophagy in chondrocytes with Kashin-Beck Disease (KBD). To clarify the potential role of autophagy-related ATG4C gene in the development of KBD, we conducted an integrative analysis of genetic association, messenger ribonucleic acid (mRNA) and protein expression of ATG4C in KBD patients.
  
  
  
  1026 subjects (559 KBD patients and 467 healthy cases) were enrolled in discovery association study. Four single nucleotide polymorphisms (SNPs) of ATG4C gene (rs11208030, rs4409690, rs12097658 and rs6587988) were genotyped by Sequenom MassARRAY platform. Association analysis was conducted by PLINK software. The significant SNPs of ATG4C were replicated using an independent sample of 899 subjects (including 90 KBD patients and 809 healthy controls). Ungenotyped SNPs in ATG4C gene were imputed by IMPUTE 2.0. Knee cartilage specimens were collected from five KBD patients and five healthy subjects. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were performed to compare the mRNA and protein expression levels of ATG4C between KBD cartilage and control cartilage.
  
  
  
  We observed significant association between KBD and rs11208030 (P value = 0.003), rs4409690 (P value = 0.004), rs12097658 (P value = 0.003) and rs6587988 (P value = 0.003) in both discovery and replication samples. The mRNA expression level of ATG4C (ratio = 0.168, P value = 0.007) in KBD chondrocytes was significantly lower than that in normal chondrocytes. Western blot (P value < 0.001) further confirmed the reduced expression of ATG4C protein in both KBD cartilage and chondrocytes.
  
  
  
  Our results strongly suggest that ATG4C was a novel autophagy-related susceptibility gene of KBD.
authors.affiliation: Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, PR China.
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.affiliation: Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, PR China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wen
authors.affiliation: Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, PR China.
authors.forename: X
authors.initials: X
authors.lastname: Guo
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Ministry of Education, and Institute of Molecular Genetics, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China.
authors.forename: T
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA; Center for Bioinformatics and Genomics, Tulane University, New Orleans, LA, USA.
authors.forename: H
authors.initials: H
authors.lastname: Shen
authors.affiliation: Laboratory of Molecular and Statistical Genetics, College of Life Sciences, Hunan Normal University, Changsha, PR China.
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA; Center for Bioinformatics and Genomics, Tulane University, New Orleans, LA, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Tian
authors.affiliation: Laboratory of Molecular and Statistical Genetics, College of Life Sciences, Hunan Normal University, Changsha, PR China.
authors.forename: L
authors.initials: L
authors.lastname: Tan
authors.affiliation: Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA; Center for Bioinformatics and Genomics, Tulane University, New Orleans, LA, USA.
authors.forename: H-W
authors.initials: HW
authors.lastname: Deng
authors.affiliation: Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, School of Public Health, Health Science Center, Xi'an Jiaotong University, Xi'an, PR China. Electronic address: fzhxjtu@mail.xjtu.edu.cn.
authors.forename: F
authors.initials: F
authors.lastname: Zhang
mesh_terms: D000328:Adult; D001343:Autophagy / Q000235:genetics; D000071186:Beclin-1 / Q000235:genetics*; D015153:Blotting, Western; D016022:Case-Control Studies; D019902:Chondrocytes / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D056726:Genetic Association Studies; D006801:Humans; D057767:Kashin-Beck Disease / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000071186:Beclin-1; D012333:RNA, Messenger
keywords: ATG4C; Autophagy; Cartilage; Kashin–Beck disease