“…With regard to ethnic groups, ten studies (67%) were done with the Asians population [ 36 , 37 , 40 – 42 , 44 – 48 ], while five studies (33%) were with the non-Asian population [ 34 , 35 , 38 , 39 , 43 ]. Ten studies were hospital-based studies [ 34 , 35 , 37 – 40 , 42 , 43 , 45 – 48 ], while 5 studies were done on patients at the outpatient clinic/special clinic [ 35 , 36 , 39 , 43 , 44 ]. Eight studies (53%) examined more than one SNP [ 32 , 34 , 40 – 42 , 44 , 45 , 45 ], while nine [ 32 , 34 – 36 , 38 – 42 , 45 ], eight [ 34 , 36 , 38 , 40 – 44 , 47 ], and 11 studies [ 32 , 36 , 37 , 40 – 42 , 44 – 48 ] examined the single SNP − 1082 A/G, -819 T/C, and − 592 A/C, respectively.…”