Table 4.

Relevant pharmacogenetics association studies that focused on tryptophan hydroxylase 1 and 2 (TPH1 and TPH2)

Reference	Gene	Drug	Sample	Outcome measure	Results	p-value
[55]	TPH1	Citalopram	105 subjects	HAMD	The remission rate was worse in A/A and A/C genotypes, even though the response rate did not differ between genotypes	p = 0.017
[56]	TPH1	Various	93 MDD patients and 127 controls	HAMD	No association either with depressive phenotype or with antidepressant response	Not significant
[57]	TPH1	Fluvoxamine or paroxetine	221 MDD patients	HAMD	Lack of association	Not significant
[48]	TPH1, TPH2	Fluoxetine	96 MDD patients	CGI	Three variations within the TPH1 differentiated responders from non-responders. Three variations in the TPH2 differentiated responders from specific and non-specific (fast antidepressant onset and lack of persistence)	0.020 <p <0.042
[4]	TPH1	Fluvoxamine	217 MDD patients	HAMD	A/A genotype was associated with slower response (no pindolol)	p = 0.001
[58]	TPH1	Paroxetine	121 MDD patients	HAMD	A/A and A/C genotypes were associated with slower response (no pindolol)	p = 0.005

Abbreviations: MDD, major depressive disorder; HAMD, Hamilton Rating Scale for Depression; CGI, Clinical Global Impression scale