Serologic and molecular investigations of a chimera

A chimeric individual possesses two or more genetically distinct ceil populations. Although the chimerism may not be evident in all gene systems, various loci display greater numbers of alleles than genetically “normal” individ uals. The proposit’a was referred for further laboratory investigation due to a mixed-field ABO blood group reaction following routine antenatal testing. Various molecular (HLA class II, ABO genotyping, and 10 short tandem repeat [STR] microsatellites) and serologic (HLA class I and red cell blood groups) typing techniques were employed to investigate a number of polymorphic loci located on different chromosomes. Chimerism was identified in 8 out of the 1.4 chromosomes tested: chromosome 1 (Duffy), 6 (HLA class I and Iï), 9 (ABO), 11 (HUMTH01), 12 (HUMPLA2A1), 15 (HUMFES/FPS). 18 (Kidd) and 21 (D21S11). The proposita was determined to be a probable dispermic chimera, based on the results of the serology and molecular studies.