GSTM1 and laryngotracheoesophageal cleft: For all included studies, Table 1 (summary schema) and Table 2 (detailed pooled analyses) presented increased risk of LC with GSTM1 deletion (RR = 1.10, p < 0.0001), while GSTM1 present genotype were protective against LC (RR = 0.91, p < 0.0001).