DNA typing in cases of blood chimerism

Abstract

A chimera is an organism whose cells derive from two or more distinct zygote lineages. and therefore two different blood cell populations circulate in one individual. To point out the potential pitfalls in forensic analysis, a set of triplets (a girl and two boys) who revealed blood chimerism was investigated with four STR systems using PCR. The results indicated that a DNA profile based on DNA extracted from blood can lead to a false determination because the band pattern of each triplet contained a mixture of the original genotype and the genotype of the siblings. Additional investigations on biological materials other than blood must be made in order to find out the real genetic characteristics of each child.

Scientific and forensic standards for homologous blood transfusion anti-doping analyses

“…Demonstrating that a mixed RBCs population is due to transplantation or transfusion should be trivial for any athlete. However, to establish chimerism, DNA analyses may be required [18]. Natural chimera frequency appears to be lower than 1 in 1 million.…”

“…However pathology-linked chimerism is easy to prove [5][6][7][8], and natural chimera frequency in adults is extremely low-less than 1 in 1 million, when measured using national blood bank data [9][10][11][12][13][14][15][16][17]. An athlete can easily prove that he or she is a chimera through blood group or mucosal DNA analyses [18]. Importantly, at the time of the writing of this report, only one occurrence of an adult chimera that was not stable over time has been documented [19], and in this case neither of the two populations ever disappeared entirely.…”

Mother–child exclusion due to paternal uniparental disomy 6

“…In chimera, the blood cells do not necessarily represent the true genotype of the individual. The genotype of blood chimera, however, can be identified by analyzing the DNA from hair follicles, which corresponds to the true genotype [7,13].…”

Can post-mortem blood be used for DNA profiling after peri-mortem blood transfusion?

“…Microchimerism in women after pregnancy has also been observed [22] but did not interfere with standard forensic Y chromosome testing so will not be considered as a potential problem in issues surrounding microchimerism following blood transfusion. Finally, it must also be noted that cases of naturally occurring microchimeric DNA profiles have been observed to be shared between triplets [23] and dizygotic twins [24]. This issue is however unrelated to the issues surrounding blood transfusion and organ transplantation and cannot be predicted at this time.…”