Low C4, C4A and C4B gene copy numbers are stronger risk factors for juvenile-onset than for adult-onset systemic lupus erythematosus

• Published in: Rheumatology (Oxford, England) England), 2016-05, Vol.55 (5), p.869-873
• Main Authors: Pereira, Kaline M C, Faria, Atila G A, Liphaus, Bernadete L, Jesus, Adriana A, Silva, Clovis A, Carneiro-Sampaio, Magda, Andrade, Luis E C
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age Factors; Age of Onset; Aged; Case-Control Studies; Complement C4 - deficiency; Complement C4 - genetics; Complement C4a - genetics; Complement C4b - genetics; Female; Gene Dosage; Genetic Predisposition to Disease; Humans; Lupus Erythematosus, Systemic - complications; Lupus Erythematosus, Systemic - genetics; Lupus Erythematosus, Systemic - immunology; Male; Middle Aged; Pericarditis - etiology; Pericarditis - genetics; Pericarditis - immunology; Risk Factors; Young Adult
• ISSN: 1462-0324; 1462-0332
• DOI: 10.1093/rheumatology/kev436

Complete deficiency of Complement C4 component is a strong genetic risk factor for SLE. C4 is encoded by two different genes, C4A and C4B, which show considerable gene copy number (GCN) variation. This study investigates the association of total C4, C4A and C4B GCN with JSLE. Ninety JSLE patients, 170 adult-onset SLE (aSLE) patients and 200 healthy individuals were evaluated for C4A and C4B GCN by quantitative real-time PCR. JSLE patients had lower GCN for C4A (mean = 1.7; 95% CI: 1.5, 1.9) and C4B (mean = 1.5; 95% CI: 1.3, 1.6) compared with healthy individuals (mean C4A = 2.3; 95% CI: 2.2, 2.5, P < 0.001; C4B = 2.0; 95% CI: 1.8, 2.1; P < 0.001) or with aSLE patients (mean C4A = 1.9; 95% CI: 1.8, 2.1, P = 0.006; mean C4B = 1.8; 95% CI: 1.7, 1.9, P < 0.001). Low total C4 GCN (