Genotype-dependent associations between serotonin transporter gene (SLC6A4) DNA methylation and late-life depression

Table 3 Adjusted associations between depression and SLC6A4 promoter methylation, stratified by 5-HTTLPR or 5-HTTLPR/rs25531 genotype

CpG unit	Genotype	Variables	Unadjusted		Adjusted^a
CpG unit	Genotype	Variables	β(SE)	p-value	β(SE)	p-value
21	5-HTTLPR (LL)	Depression	0.24 (0.39)	0.026	0.28 (0.41)	0.016
		Female sex			− 0.092 (0.39)	0.39
		Age (yrs)			0.024 (0.036)	0.83
		Antidepressants			−0.15 (0.83)	0.18
	5-HTTLPR (SS)	Depression	−0.38 (0.52)	0.004	−0.44 (0.54)	0.001
		Female sex			−0.17 (0.58)	0.22
		Age (yrs)			−0.03 (0.068)	0.82
		Antidepressant			0.13 (0.96)	0.33
		Living alone			0.38 (0.69)	0.018
	5-HTTLPR/rs25531 (L’L)	Depression	0.33 (0.49)	0.019	0.36 (0.53)	0.019
		Female sex			0.074 (0.48)	0.60
		Age (yrs)			−0.005 (0.057)	0.97
		Antidepressant			−0.093 (1.3)	0.54
	5-HTTLPR/rs25531 (S’S′)	Depression	−0.28 (0.49)	0.027	−0.30 (0.50)	0.023
		Female sex			−0.14 (0.49)	0.29
		Age (yrs)			−0.22 (0.59)	0.097
		Antidepressant			0.098 (0.87)	0.44
		Living alone			0.27 (0.60)	0.056
25.26	5-HTTLPR (SS)	Depression	−0.37 (1.58)	0.009	−0.31 (1.68)	0.038
		Sex			−0.26 (1.65)	0.068
		Age (yrs)			−0.076 (0.20)	0.60
		Antidepressant			−0.087 (3.06)	0.56
	5-HTTLPR/rs25531 (S’S′)	Depression	−0.37 (1.53)	0.006	−0.31 (1.52)	0.020
		Sex			−0.19 (1.46)	0.13
		Age (yrs)			−0.26 (0.18)	0.046
		Antidepressant			−0.11 (2.71)	0.39

^aAdjusted for age, sex and antidepressant use, plus confounding factors (see methods) which remained significant in the final models at p < 0.15

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