The correlation of vitamin D level and vitamin D-binding protein gene polymorphism in chronic obstructive pulmonary disease / 中华内科杂志

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,250participants,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 (rs4588and 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 (r2 =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.