CBLIF and vitamin B12 deficiency: Additionally, polymorphisms in the genes involved in vitamin B12 absorption and metabolism are associated with NTDs, such as mutations in exons 1 and 3 of the gastric intrinsic factor gene, variants in the lipoprotein-related protein 2 gene, alterations in the transcobalamin receptor gene, and the well-documented C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene, which is in part related to vitamin B12 deficiency [28,64,65,66,67].