Table 1.

Characteristics of the investigated studies of the association between small ubiquitin-like modifier 4 (SUMO4) gene M55V polymorphism and T2DM.

Reference	Year	Ethnicity	T2DM			Control			Matching criteria	Genotype method	Sample size (T2DM/control)
			MM	MV	VV	MM	MV	VV
Pu et al. (16)	2012	Chinese	160	218	26	250	218	32	Age, sex, ethnicity	PCR-HRM	404/500
Li et al. (22)	2011	Chinese	110	94	28	44	51	7	Ethnicity	PCR-RFLP	232/102
Shimada et al. (23)	2009	Japanese	395	393	86	412	414	79	Ethnicity	TaqMan SNP genotyping assay	874/905
Lin et al. (24)	2010	Chinese	275	254	45	186	115	22	Ethnicity	PCR-RFLP	574/323
Noso et al. (15)	2007	Japanese	146	166	43	200	158	40	Ethnicity	TaqMan SNP genotyping assay	355/398
Fallah et al. (17)	2010	Iranian	10	22	18	13	25	12	Age, sex, ethnicity	PCR-RFLP	50/50
Ji et al. (7)	2010	Chinese	195	185	46	143	123	15	Age, sex, ethnicity	PCR-RFLP	427/281
Hu and Song (25)	2009	Chinese-Va	59	31	6	68	33	3	BMI, ALT, Cr, UA, TC, TG, HDL-C, LDL-C, ethnicity	PCR-RFLP	96/104
Hu and Song (25)	2009	Chinese-Lalu	40	11	3	168	60	6	Age, sex, ethnicity, BMI, WHR, SBP, DBP, HDL-C, Hypertension percentage	PCR-RFLP	54/234
Wang et al. (26)	2015	Chinese	45	54	1	249	218	32	Age, BMI, DBP, TG, LDL-C, ethnicity	PCR-RFLP	100/499
Zhang et al. (27)	2017	Chinese	25	22	11	105	90	9	Sex, BMI, Hypertension percentage, Hyperlipidemia percentage	PCR-RFLP	58/204

T2DM, type 2 diabetes mellitus; TC, total cholesterol; LDL, low-density lipoprotein-cholesterol; PCR-RFLP, polymerase chain reaction-restriction fragment length polymorphism; PCR-HRM, polymerase chain reaction-high resolution melting curve.

PCR-RFLP and case–control study design were adopted in the above studies.