Technical Abstract: A genome-wide scan is a way to distinguish small differences in the genetic makeup of individuals. It is also a way which distinguishes if a mutation in any particular gene is widespread or it is "polymorphic." The value of these analyses lies in the identification of genes that could influence a the outcome of a disease or other "phenotypic" features. In this study we find that a gene which codes for an enzyme called FUT2 affect the level of vitamin B12 in the blood. A specific mutation in this gene is associated with higher vitamin B12 level in blood. The link between FUT2 and B12 is that FUT2 is responsible for the secretion in the stomach of H antigen which renders the person more susceptible for infection by H pylori which may cause ulcers. People with this mutation do not secrete their antigen. Absorption of vitamin B12 requires an intrinsic factor which is also secreted by stomach.