Allogeneic hematopoietic stem cell transplantation is a curative treatment for malignant hematologic diseases, leukemias, congenital and acquired non-malignant diseases of a patient (recipient) by replacing recipients cells by new one from a healthy donor. Monitoring of hematopoietic chimerism after allogenic transplantation is a useful tool for determining the engraftment of donor cells and predicting the risk of relapse of the original disease. Nowadays, diverses techniques are used and differ from laboratory to laboratory, which make data exchange and comparaison between them difficult. Amplification of short tandem repeats (PCR-STR) constitutes the gold standard method for chimerism quantification, although more sensitive PCR techniques have recently developed. This study was carried out on 30 allografted patients in whom the status of chimerism was analysed by the use of STRs included in Investigator Id-plex plus kit (Qiagen). This is conducted by taking samples of whole blood from these patients at different times in post-allograft from which we extract DNA and amplify STR markers and genotyped by capillary electrophoresis. The STR profiles have been generated for each sample including donor and recipient samples taken before the allogeneic transplant (J0). Profiles comparison obtained from the post-allograft samples with the genotypes of the donor and the pre- allograft recipient, permits to determine the status of chimerism in these different patients. This work was preceded by analyzing a set of 219 individual from Morocco with the objective to establish their usefulness for human identification. Allelic frequencies for the 15 short tandem repeat (STRs) loci were calculated. Results show that the 15 loci are highly polymorphic. The combined power of exclusion for the fifteen loci is 0.99999968 and the combined discrimination indice was 0.999999999999999985. The combined matching probability for these loci reaches 1.59 10-18 which make these loci very useful for personal identification casework purposes in Morocco.

Keywords : Chimerism; STR; Morocco; Allogenic Transplanted Patients; Investigator IDPlex Plus; Informativity; Polymorphism, Forensic Parameters