Genetic variants of pulmonary SP‐D predict disease outcome of COPD in a Chinese population. Issue 2 (6th November 2014) - Ou, Chih‐Ying
Abstract Background and objective Although surfactant protein‐D (SP‐D) has been suggested as a biomarker for chronic obstructive pulmonary disease (COPD), the relationship between genetic variants of SP‐D and disease outcome of COPD remains unknown. We hypothesized that genetic polymorphisms of SP‐D are associated with COPD‐related phenotypes and disease prognosis. Methods A hospital‐based, case‐controlled study was conducted prospectively. Six single nucleotide polymorphisms of the SFTPD gene were determined for genetic association analysis. Inflammatory cytokines and SP‐D serum level were quantified. Frequency of exacerbation and change of lung function were assessed. All‐cause 3‐year mortality was registered. Results We studied 320 smokers (192 with COPD and 128 at‐risk for COPD) who were prospectively monitored for at least 3 years. The serum levels of SP‐D in COPD patients were significantly associated with the degree of airflow obstruction and frequency of exacerbation. Haplotype association analysis revealed that haplotype G‐G‐C‐C‐A was associated with lower risk of COPD (P = 0.03) in our study population. COPD patients with haplotype G‐G‐C‐C‐A had lower serum SP‐D levels (P < 0.001), higher rates of positive response to bronchodilator treatment (P = 0.01), more improvement of forced expiratory volume in 1 s in yearly follow‐up (P = 0.03) and better 3‐year survival rate than COPD patients with non G‐G‐C‐C‐A haplotype (P = 0.03). Conclusions Genetic haplotype of SP‐D may serve as a valuable prognostic indicator in Chinese patients with COPD.