Relationships have been identified between renal involvement and early disease onset; neurological involvement and disease duration; between low C4, hypergammaglobulinemia, interstitial lung disease, and cough; and between dyspnea, Raynaud’s phenomenon, antiSSA/Ro52, leukocytopenia, and low C3, hypergammaglobulinemia, and antiSSA/Ro [19–21]. This evidence concerns the gene C4A and interstitial lung disease.