Molecular Analysis of BMPR2, TBX4, and KCNK3 and Genotype-Phenotype Correlations in Spanish Patients and Families With Idiopathic and Hereditary Pulmonary Arterial Hypertension.

INTRODUCTION AND

OBJECTIVES

Recent advances in genetics have led to the discovery of new genes associated with pulmonary arterial hypertension, such as TBX4 and KCNK3. The phenotype and prognosis associated with these new genes have been scarcely described and their role in the Spanish population is unknown. The aim of this study was to characterize the genetics of a Spanish cohort of patients with idiopathic and hereditary pulmonary arterial hypertension and to describe the phenotype and prognostic factors associated with BMPR2 and the new genes (KCNK3 and TBX4).

METHODS

A total of 165 adult patients were screened for BMPR2, KCNK3, and TBX4 mutations, 143 with idiopathic pulmonary arterial hypertension and 22 with hereditary pulmonary arterial hypertension. Baseline characteristics and survival were compared among the different subgroups and predictors of poor outcomes were analyzed. We also performed family screening.

RESULTS

The genetic study identified a possibly associated mutation in 11.10% of the idiopathic cases (n = 16) and in 68.18% of the hereditary cases (n = 15). There were 19 mutations in BMPR2, 4 in TBX4, and 3 in KCNK3. The forms associated with TBX4 showed the highest survival rate (P < .01). Advanced functional class at diagnosis was the only factor associated with poor outcomes in the hereditary forms. In the family screening, 37.5% of relatives tested positive.

CONCLUSIONS

The genetics of pulmonary arterial hypertension in the Spanish population may differ from other populations, with a lower proportion of BMPR2 causative mutations. In our cohort, TBX4-related forms of pulmonary arterial hypertension showed a more benign course and late diagnosis was the only predictor of adverse outcomes in the hereditary forms of the disease.