The Dombrock blood group system (DO) is a common polymorphism in Cauca
sians, represented by two red cell antigen alleles. In a linkage study
in our family material of 832 families from the Copenhagen area, we f
ound a strong indication of tight linkage with the two flanking DNA po
lymorphisms D12S358 (z = 7.66; at theta(M) = 0.001, theta(F) = 0.031)
and D12S364 (z = 8.53; at theta(M) = 0.068, theta(F) = 0.031), DO is a
ssigned to the region 12p13.2-12p12.1 by physically localised markers.