Table 2.

Relevant studies on 235delC mutation and NSHL

No	Author	Score/ Grade	No	Author	Score/ Grade
Studies in non-Asian populations
1	Dahl HM, et al. 2006 [4]	6A	7	Cheng X, et al. 2005 [23]	5B
2	Ramsebner R, et al. 2007 [5]	5B	8	Utrera R, et al. 2007 [33]	5B
3	Batissoco AC, et al. 2009 [11]	5B	9	Tang HY, et al. 2006 [20]	6A
4	Damalon V, et al. 2010 [34]	5B	10	Pollak A, et al. 2007 [35]	5B
5	Samanich J, et al. 2007 [36]	5B	11	Tóth T, et al. 2007 [37]	5B
6	Schimmenti LA, et al. 2008 [17]	6A	12	Neocleous V, et al. 2006 [38]	5B
Studies in East Asian and Southeast Asian populations
13	Snoeckx RL, et al. 2005 [39]	5B	23	Xiao ZA, et al. 2004 [26]	5B
14	Wattanasirichaigoon D, et al. 2004 [12]	5B	24	Wang SH, et al. 2009 [ 27]	6A
15	Park HJ, et al. 2000 [14]	6A	25	Hwa HL, et al. 2003 [28]	5B
16	Lee KY, et al. 2008 [16]	5B	26	Shi GZ, et al. 2004 [29]	6A
17	Abe S, et al. 2000 [19]	5B	27	Dai P, et al. 2007 [30]	6A
18	Ohtsuka A, et al. 2003 [10]	5B	28	Liu ZX, et al. 2002 [31]	5A
19	Tekin M , et al. 2010 [21]	5B	29	Liu YH, et al. 2002 [32]	6A
20	Kudo T, et al. 2000 [22]	5B	30	Chen GM, et al. 2011 [40]	5B
21	Wang YC, et al. 2002 [24]	6A	31	Guo YF, et al. 2008 [41]	6A
22	Chen D, et al. 2009 [25]	5B
Studies in South Asian, West Asian and North Asian populations
32	Padma G, et al. 2009 [13]	6A	35	Baysal E, et al. 2008 [42]	6A
33	Bhalla S, et al. 2009 [43]	6A	36	Posukh O, et al. 2005 [18]	5B
34	Shalin H, et al. 2002 [15]	5B