ANA positivity was associated with a sensitivity of 94% (95% CI 71.3–99.9%) and a specificity of 78.1% (60–90.7%) for a diagnosis of CTD-associated-PAH; while Raynaud phenomenon was associated with a sensitivity of 83.3% (95% CI 51.6–97.9%) and a specificity of 100% (90.5–100%) for a diagnosis of SSc-associated-PAH. This evidence concerns the gene BTG3 and systemic sclerosis.