A burden of rare variants in BMPR2 and KCNK3 contributes to a risk of familial pulmonary arterial hypertension

Background: Pulmonary arterial hypertension (PAH) is a severe lung disease with only few effective treatments available. Familial cases of PAH are usually recognized as an autosomal dominant disease, but incomplete penetrance of the disease makes it difficult to identify pathogenic variants in accordance with a Mendelian pattern of inheritance. Methods: To elucidate the complex genetic basis of PAH, we obtained whole exome- or genome-sequencing data of 17 subjects from 9 families with heritable PAH and applied gene-based association analysis with 9 index patients and 300 PAH-free controls. Results: A burden of rare variants in BMPR2 significantly contributed to the risk of the disease (p=6.0×10-8). Eight of nine families carried four previously reported single nucleotide variants and four novel insertion/deletion variants in the gene. One of the novel variants was a large 6.5 kilobase-deletion. In the remaining one family, the patient carried a pathogenic variant in a member of potassium channels, KCNK3, which was the first replicative finding of channelopathy in an Asian population. Conclusions: The variety of rare pathogenic variants suggests that gene-based association analysis using genome-wide sequencing data from increased number of samples is essential to tracing the genetic heterogeneity and developing an appropriate panel for genetic testing.