The individual allele of SNP5G, SNP6A, SNP7G and SNP8T were associated with rapid decline in FEV1 despite smoking cessation, when 82 COPD patients (ex-smokers) were prospectively followed up for 30 months and evaluated the differences among the genotypes in the annual rate of decline in FEV1 with ten SNPs in and around the cell division cycle 6 (CDC6) gene 72. Here, CDC6 is linked to chronic obstructive pulmonary disease.