Chimerism quantification after sex-matched BMT: How probable is it to finddonor/recipient pairs with distinguishable cells?

Chimerism quantification (CQ) after sex-matched bone mal? ow transplantatio n (BIMT) is based on the identification of autosomal differences distinguis hable at the chromosomal level, such as variations within constitutive hete rochromatin between the recipient and the donor. The probability of finding distinguishable recipient/donor pairs at the karyotypic level depends on t he frequency of the chromosome variants or morphs in the population, on whe ther recipient and donor are related, and if so, their kinship relation. We have developed a population genetics-based method that allows the estimati on of the percentage of post-BMT CQ expected to be informative using any au tosomal polymorphic marker. This method has been developed for the most com mon transplant situations, such as sibling-matched recipient/donor pairs, h aploidentical related (parental/filial) pairs, and unrelated pairs. The met hod developed was applied to a polymorphism of the pericentromeric region o f chromosome 3. This polymorphism becomes evident after in situ digestion w ith the restriction endonuclease Sau3A, and can be successfully used for CQ . It has been estimated that approximately 59% of the cases of BMT from unr elated donors, 36% of those from sibling donors, and 42% from parental/fili al donors, are expected to be distinguishable for post-BMT CQ using this ap proach. (C) Elsevier Science Inc., 1999. All rights reserved.