AIM: Autophagy-related gene 5 (ATG5), ATG7, B-lymphoid tyrosine kinase (BLK) and 
B-cell scaffold protein with ankyrin repeats 1 (BANK1) are involved in B-cell 
signaling; several genome-wide association studies detected these genes as 
candidates involved in systemic lupus erythematosus (SLE). We aimed to replicate 
the association of these genes with SLE in Chinese Han and to search for 
possible gene-gene interactions.
METHODS: TaqMan single-nucleotide polymorphism (SNP) genotyping was used to 
detect rs548234, rs665791 in ATG5, rs11706903 in ATG7, rs2736340 in BLK and 
rs10516487 in BANK1 in 382 SLE patients and 660 healthy controls. The epistasis 
effect was analyzed by logistic regression, multifactor dimensionality reduction 
(MDR) and linear regression analysis.
RESULTS: SLE was associated with frequency of rs548234 (P = 0.010; odds ratio 
[OR] = 1.298), rs2736340 (P = 2.47 × 10-5 ; OR = 1.574) and rs10516487 (P = 
0.002; OR = 0.642). Although no epistasis effects were found among three 
autophagy-related gene loci or with rs2736340 and rs10516487, BLK and BANK1 had 
the closest interaction effect on logistic regression analysis (P = 0.013; OR = 
1.205), MDR (P < 0.0001), and linear regression analysis (P = 0.0017; R2 = 
0.1806). The risk genotype TT of rs2736340 was associated with decreased 
messenger RNA level of BLK; BLK transcript level was lower in SLE patients than 
healthy controls.
CONCLUSION: We confirmed the association of rs548234, rs2736340 and rs10516487 
with SLE in Chinese Han and reinforced our hypothesis of their epistasis effect 
in regulating B-cell signaling in SLE.