HP and duodenal ulcer: DQA1*03:01 was found to be often in both CD and HP-positive duodenal ulcer patients (Azuma et al., 1995; Mubarak et al., 2013). TNF-308 (G > A) SNP increases risk of CD and persistent HPinfection (Khan et al., 2016). The−336G CD209 allele# associated with a higher HP infection severity/susceptibility might be involved in CD susceptibility in HLA-DQ2 negative patients. (Núñez et al., 2006).