Relationship between vitamin D-binding protein polymorphisms and blood vitamin D level in Korean patients with COPD.
BACKGROUND
In chronic obstructive pulmonary disease (COPD), the blood vitamin D3 level is generally low, and genetic polymorphisms of vitamin D-binding protein encoded by the GC gene are associated with COPD development. In this study, we examined the relationship between GC polymorphisms and plasma vitamin D3 level in Korean patients with COPD.


METHODS
The study included 175 COPD patients from the Korean Obstructive Lung Disease Cohort. Multivariate analysis was conducted with adjustment for age, body mass index (BMI), lung function, smoking status, smoking amount, and seasonal variation in blood vitamin D level. Vitamin D deficiency was defined as a plasma 25-hydroxyvitamin D3 level lower than 20 ng/mL.


RESULTS
The mean plasma vitamin D3 level was 17.5 ng/mL. The GC1F variant (44.3%) and genotype 1F-2 (27.4%) were the most common. The plasma vitamin D3 level was lower in patients with the GC2 variant (estimated =-3.73 ng/mL) and higher in those with genotype 1F-1S (estimated =4.08 ng/mL). The GC2 variant was a significant risk factor for vitamin D deficiency (odds ratio =2.41). Among COPD clinical parameters, vitamin D deficiency was associated with a lower ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) regardless of GC polymorphisms. FEV1/FVC was higher in patients with genotype 1F-1F (estimated =3.61%) and lower in those with genotype 1F-2 (estimated =-3.31%). The 6-minute walking distance was shorter for patients with the GC1F variant (estimated =-38.91 m) and longer for those with the GC2 variant (estimated =26.98 m). The emphysema index was higher for patients with the GC1S variant (estimated =6.56%) and genotype 1F-1S (estimated =9.86%), regardless of the vitamin D level.


CONCLUSIONS
The GC2 variant is a risk factor for vitamin D deficiency, and genotype 1F-1S is a protective factor against vitamin D deficiency. GC polymorphisms and vitamin D deficiency correlate with clinical outcomes for Korean patients with COPD.
Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea.
Youngmok
Y
Park
Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea.
Young Sam
YS
Kim
Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea.
Young Ae
YA
Kang
Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea.
Ju Hye
JH
Shin
Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Yeon Mok
YM
Oh
Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Joon Beom
JB
Seo
Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Institute of Chest Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea.
Ji Ye
JY
Jung
Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Sang Do
SD
Lee
D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000235:genetics*; D056910:Republic of Korea; D014807:Vitamin D / Q000097:blood*; D014809:Vitamin D-Binding Protein / Q000235:genetics*
D014809:Vitamin D-Binding Protein; D014807:Vitamin D
chronic obstructive pulmonary disease; polymorphism; vitamin D; vitamin D-binding protein