DNA typing in cases of blood chimerism.

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.