title: [The correlation of vitamin D level and vitamin D-binding protein gene polymorphism in chronic obstructive pulmonary disease].
abstract: OBJECTIVE
  To assess the correlation of serum 25-hydroxyvitamin D (25-OHD) levels with vitamin D-binding protein (the group-specific component, GC) gene polymorphism in chronic obstructive pulmonary disease (COPD).
  
  
  METHODS
  In a cross-sectional case-control study, 250 participants, including 116 COPD patients with smoking history and 134 healthy smokers, were investigated. A questionnaire about smoking history, vitamin D intake and comorbidities was collected. General pulmonary function was done by routine. Serum 25-OHD levels were detected by ELISA. The genetic variants (rs4588 and rs7041) were genotyped by real time fluorescence polymerase chain reaction (RT-PCR) with TaqMan probe technology.
  
  
  RESULTS
  The COPD patients had lower serum vitamin D level than the smoker subjects (36.58 nmol/L vs 43.80 nmol/L, P < 0.001). In the COPD patients, vitamin D level was 39.43 nmol/L in those with percentage of predicted forced expiratory volume in 1 second (FEV1%pred) greater than or equal to 80%.In other groups with FEV1%pred 50%-80%, 30%-50% and lower than 30%, vitamin D levels were 35.32 nmol/L, 32.21 nmol/L, 26.25 nmol/L respectively (P < 0.01). Moreover, there was a significant relevance of 25-OHD levels with FEV1%pred in both COPD patients and healthy smokers (r(2) = 1.911; P < 0.000 1). The mean 25-OHD concentration had a negative correlation with Global Initiative for Obstructive Lung Disease (GOLD) stages. Homozygous carriers of vitamin D-binding protein gene rs7041 T allele were independently related to 25-OHD levels and susceptibility of COPD (P < 0.01; OR = 2.140, 95%CI 1.157-3.959, P = 0.015 respectively).
  
  
  CONCLUSIONS
  Patients with COPD are at high risk of vitamin D deficiency and the severity of COPD is inversely correlated with vitamin D levels. Furthermore, homozygous carrier of rs7041 T allele influences 25-OHD serum levels and is related to susceptibility of COPD, which may be a potential candidate gene for screening COPD.
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China. Email: liuxiansheng69@gmail.com.
authors.forename: Xiansheng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Yongjian
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Weining
authors.initials: W
authors.lastname: Xiong
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Ni
authors.affiliation: Department of Respiratory Diseases, Tongji Hospital, Key Lab of Pulmonary Diseases of Health Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Shixin
authors.initials: S
authors.lastname: Chen
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000235:genetics*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014809:Vitamin D-Binding Protein / Q000235:genetics*
chemical_list: D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D