Higher Genetic Risk Loads Confer More Diverse Manifestations and Higher Risk of Lupus Nephritis in Systemic Lupus Erythematosus

Abstract

Objective: Systemic lupus erythematosus (SLE) is a highly heritable complex disorder with heterogeneous clinical manifestations. In this study, we aimed to identify the genetic risk load using clinical and serological manifestations in SLE patients.

Methods: We genotyped a total of 1,655 Korean patients with SLE (n = 1,243 as a discovery set and n = 412 as a replication set) using a customized genome-wide single-nucleotide polymorphism (SNP) array, KoreanChip. A weighted genetic risk score (wGRS) for an individual was calculated from 112 well-validated non-HLA SNPs and HLA haplotypes of SLE-risk loci. We analyzed associations between individual wGRS and clinical SLE subphenotypes and autoantibodies using multivariable linear or logistic regression adjusted by onset age, sex, and disease duration.

Results: Childhood-onset SLE (<16 years) conferred the highest genetic risk compared with adult-onset (16-50 years) or late-onset (>50 years) SLE (P = 6.8 × 10^-6 ). High wGRS significantly increased associations with SLE manifestations, regardless of onset age, sex, and disease duration. Individual wGRS significantly correlated positively with more clinical American College of Rheumatology criteria (β = 0.143, P = 1.8 × 10^-6 ). Subphenotype analysis revealed significant associations between the highest and lowest wGRS quartile with risk of renal disorder (hazard ratio [HR] 1.74, P = 2.2 × 10^-8 ) and anti-Sm antibody production (HR 1.85, P = 2.8 × 10^-5 ). Higher wGRS markedly modulated the pathogenesis of proliferative and membranous lupus nephritis class III or IV (HR 1.98, P = 1.6 × 10^-5 ) and class V (HR 2.79, P = 1.0 × 10^-3 ), but especially lupus nephritis class V in anti-Sm-positive SLE (area under the curve 0.68, P = 1.8 × 10^-4 ).

Conclusion: Patients with SLE and high wGRS tended to have earlier age of SLE onset, higher anti-Sm antibody positivity, and more diverse clinical phenotypes. Genetic profiling may predict high risk for lupus nephritis and a diverse clinical course in SLE patients.