Objective To investigate the relevance of genetic alterations in the Kv1.5 channel gene(KCNA5) to the development of idiopathic pulmonary arterial hypertension(IPAH) in Chinese Han nationality.Methods IPAH patients(n=86) were recruited from Chinese Han nationality.Randomized control samples(n=250) were obtained from the same population.Genomic DNA was extracted from peripheral blood of all samples.The coding,the noncoding regions and the enhancer region of the KCNA5 gene were amplified by using primers sets with optimal annealing temperature.All amplificants were directly sequenced.Hemodynamic data were compared between patients with and without KCNA5 gene variants.Results The frequency of the variant KCNA5 C-862G was found statistically different between the patients and the control samples.Moreover,there was marked difference between the patients with and without the variant.Conclusion Genetic variant KCNA5 C-862G may alter the expression and/or function of Kv1.5 channel,which may be associated with IPAH of phenotype.