Gene Mapping Determination of the relative positions of genes on a DNA molecule(chromosome and of the distance, in linkage units or hysical units, between them o 1911, red-green color blindness localized to chromosome x 1968, Duffy Blood Group localized to chromosome 1Determination of the relative positions of genes on a DNA molecule (chromosome) and of the distance, in linkage units or physical units, between them. Gene Mapping ❖ 1911,red-green color blindness localized to chromosome X ❖ 1968, Duffy Blood Group localized to chromosome 1