Association between apolipoprotein E gene polymorphism and mild cognitive impairment: a meta-analysis

Figures & data

Table 1 Characteristics of the selected studies

Study	Year	Geographical location	Sample size (case/control)	Case									Control
				ε4ε4	ε4ε3	ε4ε2	ε3ε3	ε3ε2	ε2ε2	ε4	ε3	ε2	ε4ε4	ε4ε3	ε4ε2	ε3ε3	ε3ε2	ε2ε2	ε4	ε3	ε2
Wang et al^Citation21	2002	China (Heifei)	28/30	2	9	7	6	3	1	20	24	12	1	4	2	18	4	1	8	44	8
Gamarra et al^Citation22	2015	Spain	124/125	20	66	2	119	9	0	108	313	11	0	49	2	170	22	2	51	411	28
Wang et al^Citation23	2014	China (Wuzhong)	216/743	1	24	1	135	17	3	27	311	24	6	34	2	580	105	16	48	1,299	139
Borenstein et al^Citation24	2010	China (Shanghai)	30/32	2	5	2	20	1	0	11	46	3	0	2	1	23	6	0	3	54	7
Wang et al^Citation25	2014	China (Beijing)	56/75	0	23	1	26	3	3	24	78	10	0	8	3	51	12	1	11	122	17
Chen et al^Citation26	2016	China (Shanghai)	583/1,149	27	129	16	353	56	2	199	891	76	8	156	21	802	154	8	193	1,914	191
Chen et al^Citation27	2016	China (Ningbo)	64/54	5	20	0	35	4	0	30	94	4	0	7	0	37	10	0	7	91	10
Hu et al^Citation28	2005	China (Guangxi)	16/96	1	3	1	10	1	0	6	24	2	0	4	1	79	7	5	5	169	18
Xu et al^Citation29	2009	China (Guangzhou)	120/120	2	36	1	65	16	0	41	182	17	1	16	1	81	21	0	19	199	22
Lv and Zhong^Citation30	2012	China (Shanghai)	84/106	3	20	2	52	6	1	28	130	10	0	15	1	76	12	2	16	179	15
He et al^Citation31	2015	China (Nanchang)	120/120	4	23	1	79	12	1	32	193	15	0	17	1	83	17	2	18	200	22
Ye and Zhang^Citation32	2008	China (Wuhan)	56/89	2	15	5	31	3	0	24	80	8	1	11	1	64	12	0	14	151	13
He et al^Citation33	2015	China (Shenyang)	63/60	6	18	1	32	6	0	31	88	7	2	8	1	39	10	0	13	96	11
Yue et al^Citation34	2013	China (Nanjing)	111/90	4	25	3	66	13	0	36	170	16	0	8	0	69	13	0	8	159	13
Chen et al^Citation35	2011	China (Guiyang)	76/152	9	18	28	13	6	2	64	50	38	10	29	38	57	14	4	87	157	60
Kerr et al^Citation36	2016	Brazil	43/144	1	14	1	25	1	1	17	65	4	1	31	2	91	18	1	35	231	22
Lanni et al^Citation37	2012	Italy	70/248	2	18	2	41	7	0	24	107	9	0	27	0	201	20	0	27	449	20
Jairani et al^Citation38	2016	India	87/152	4	40	2	35	6	0	50	116	8	20	34	3	82	8	5	81	206	21

Figure 1 Flow diagram of the article selection process.

Table 2 Meta-analysis of apolipoprotein E gene polymorphism and MCI risk

Genetic models	Variables	Number of studies	Test of association			Test of heterogeneity
			OR	95% CI	P-value	I^2 (%)	Model
ε2/ε2 vs ε3/ε3	Overall	18	0.91	0.50–1.65	0.758	0	F
	Chinese	14	1.04	0.55–1.99	0.902	0	F
ε2/ε4 vs ε3/ε3	Overall	18	2.57	1.77–3.73	<0.001	0	F
	Chinese	14	2.59	1.74–3.86	<0.001	0	F
ε2/ε3 vs ε3/ε3	Overall	18	0.8	0.66–0.97	0.026	0	F
	Chinese	14	0.79	0.64–0.98	0.03	0	F
ε3/ε4 vs ε3/ε3	Overall	18	2.31	1.99–2.69	<0.001	0	F
	Chinese	14	2.34	1.97–2.79	<0.001	5.8	F
ε4/ε4 vs ε3/ε3	Overall	18	4.45	3.06–6.48	<0.001	39.6	F
	Chinese	14	5.45	3.41–8.70	<0.001	0	F
ε4 allele vs ε3 allele	Overall	18	2.38	2.11–2.68	<0.001	42.8	F
	Chinese	14	2.52	2.19–2.90	<0.001	0	F
ε2 allele vs ε3 allele	Overall	18	0.9	0.77–1.05	0.179	32.2	F
	Chinese	14	0.92	0.78–1.09	0.346	30.2	F

Note: P-value corresponding to the Z-test for the summary effect estimate (P<0.05 considered statistically significant).

Abbreviations: F, fixed effects model; OR, odds ratio; CI, confidence interval; I², heterogeneity index; MCI, mild cognitive impairment.

Figure 2 Forest plot for the association of ApoE polymorphism with MCI susceptibility in the overall populations (ε4 vs ε3).

Abbreviations: ApoE, apolipoprotein E; MCI, mild cognitive impairment; OR, odds ratio; CI, confidence interval.

Figure 3 Forest plot for the association of ApoE polymorphism with MCI susceptibility in the overall populations (ε2 vs ε3).

Abbreviations: ApoE, apolipoprotein E; MCI, mild cognitive impairment; OR, odds ratio; CI, confidence interval.

Figure 4 Sensitivity analysis of the summary of OR coefficients in the overall populations (ε4 vs ε3).

Abbreviations: OR, odds ratio; CI, confidence interval.

Figure 5 Sensitivity analysis of the summary of OR coefficients in the overall populations (ε2 vs ε3).

Abbreviations: OR, odds ratio; CI, confidence interval.

Figure 6 Begg’s funnel plot of ApoE polymorphism with MCI susceptibility in overall populations (ε2 vs ε3).

Abbreviations: ApoE, apolipoprotein E; MCI, mild cognitive impairment; OR, odds ratio; SE, standard error.

Figure 7 Begg’s funnel plot of ApoE polymorphism with MCI susceptibility in overall populations (ε4 vs ε3).

Abbreviations: ApoE, apolipoprotein E; MCI, mild cognitive impairment; OR, odds ratio; SE, standard error.

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