IRGM and Cowden disease: Additionally, autophagy-related protein 16 − 1 (ATG16L1), nucleotide-binding oligomerization domain-containing protein 2 [NOD2], immunity-related GTPase family M protein [IRGM], and leucine rich repeat kinase 2 [LRRK2] have been suggested as genetic susceptibility loci for CD based on genome-wide association studies (GWAS) [45–47].