Multiple variants in IFN genes linked to mortality and discrete phenotypes of SSc, such as dcSSc, lcSSc, anti-DNA topoisomerase I antibody (ATA), anticentromere antibodies (ACA), and pulmonary arterial hypertension (PAH), point to the importance of the IFN pathway, both in the development and progression of SSc. Here, IFNA1 is linked to pulmonary arterial hypertension.