Table 1.

Characteristics of the studies included in this meta-analysis

Study	Year	Ethnicity	Age group	Gender	No. of Case	No. of Control	Quality grade	Polymorphism
Ramasamy	2011	Caucasian	Adult	Both	3393	8965	A (scored 20)	rs1898671
Andiappan	2012	Asian	Adult	Both	1858	668	A (scored 21)	rs1898671
Zhang	2012	Asian	Adult	Both	368	325	A (scored 17)	rs12653736, rs1837253, rs12654933, rs10455025, rs11466741, rs13156086, rs6886755, rs252706, rs2416259
Birben	2014	Caucasian	Children	Both	138	157	A (scored 16)	rs3806933, rs2289276, rs10073816, rs11466749
Nilsson	2014	Caucasian	Children	Both	594	1357	A (scored 16)	rs1898671