Evidence for the role of small ubiquitin-like modifier 4 as a general autoimmunity locus in the Japanese population.

CONTEXT: Recently, an association of a single nucleotide polymorphism, 163A>G encoding M55V, in the gene SUMO4, which has been shown to be a negative feedback regulator for nuclear factor kappaB, has been reported in type 1 diabetes.

OBJECTIVE

To establish whether SUMO4 locus contributes to the genetic susceptibility to other autoimmune disorders, a case-control analysis was carried out using genomic DNA from type 1 diabetes, autoimmune thyroid disease (AITD), rheumatoid arthritis (RA), and primary Sjögren's syndrome.

SUBJECTS: A total of 1480 samples, including 929 cases (411 patients with type 1 diabetes, 292 AITD, 172 RA, and 54 primary Sjögren's syndrome) and 551 healthy control subjects of Japanese origin participated in the study.

METHODS

The 163A>G (rs237025, M55V) polymorphism of SUMO4 was genotyped.

RESULTS

SUMO4 M55V variant was associated not only with type 1 diabetes [odds ratio (OR), 1.42; 95% confidence interval (CI), 1.09-1.84; P = 0.0072], but also with increased risk of other autoimmune diseases, AITD (OR, 1.52; 95% CI, 1.14-2.03; P = 0.0041) and RA without amyloidosis (OR, 1.53; 95% CI, 1.65-2.24; P = 0.027), but not primary Sjögren's syndrome. Furthermore, the association of SUMO4 M55V variant was stronger in type 1 diabetic patients complicated with AITD (OR, 1.62; 95% CI, 1.06-2.47; P = 0.023) and in patients who have neither type 1 diabetes-susceptible class II HLA, DRB1*0405 nor DRB1*0901 (OR, 2.28; 95% CI, 1.34-3.87; P = 0.0018).

CONCLUSIONS

These results indicate that the SUMO4 is a more common autoimmune disease gene and a supplementary risk factor to type 1 diabetes in conjunction with class II HLA.