Table 1.

Characteristics of the included studies

First author	Year	Ethnity	Gender	Age	No. of patients	DM	Gene
Doney	2005	Caucasian	Mixed	64.4	2015	Type 2	GSTT1
Hovnik	2009	Caucasian	Mixed	27.4	124	Type 1	GSTM1, GSTT1
Cilensek	2012	Caucasian	Mixed	65.6	704	Type 2	GSTM1, GSTT1
Dadbinpour	2013	Caucasian	Mixed	35-65	115	Type 2	GSTM1, GSTT1
Moasser	2014	Caucasian	Mixed	52.7	605	Type 2	GSTM1, GSTT1

DM, diabetes.