Assignment of ABO locus to 9q31.3----qter by study of a family in which an intrachromosomal shift involving chromosome 9 is segregating

A family in which an intrachromosomal shift, dir ins(9) (q22.1q31.3;q34.3), was segregating is described. A meiotic crossing over in the noninsertional loop of the carrier mother appeared to have resulted in the proband with a recombinant chromosome 9 duplicating the interstitial segment 9q22.1→q31.3. The study of ABO and AK1 phenotypes in the family showed that the proband was also a recombinant for the ABO locus. These results allowed us to assign the ABO locus to 9q31.3→qter on the cytogenetic basis.