Background:
The function of the Klotho gene, originally identified by insertional mutagenesis in mice, is to suppress multiple aging phenotypes. It has been shown that a mutant Klotho gene is associated with pulmonary emphysema in mice. The aims of this study were to detect Klotho gene polymorphisms (-395G>A SNP) and to identify their possible relationships with clinical findings in patients with chronic obstructive pulmonary disease (COPD).

Methods:
In 167 patients with COPD -395G>A SNP of the Klotho gene was genotyped by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) coupled with sequencing. The possible relationship was explored of -395G>A SNP with clinical findings such as lung function parameters, staging according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD), and body mass index (BMI).

Results:
Of the 167patients with COPD, 99 (59.3%) presented the wild type -395G allele, 62 (37.1%) were heterozygotes (–395GA allele), and 6 (3.6%) presented the non-wild type–395A allele. In these COPD patients there was an association between Klotho genotypes and BMI (p=0.025). No association was found between Klotho gene polymorphism and disease severity, assessed by spirometry, arterial blood gases and GOLD stage.

Conclusion:
Klotho -395G>A polymorphisms are detected in patients with COPD and are associated with BMI, but not with various parameters of disease severity. This may suggest a possible metabolic pathway in the implication of Klotho deficient gene in the pathophysiology of emphysema in COPD patients.