[Additional chromosomal changes in impaired chimeric analysis of a patient with relapsed leukemia after bone marrow...

Chimerism analysis by polymerase chain reaction amplification of short tandem repeats (PCR-STR) has become a routine diagnostic procedure for evaluating grafts and assessing the likeliness of original disease recurrence after allogeneic stem cell transplantation. Following a sex-mismatched hematopoietic stem cell transplantation (HSCT), we monitored the clinical course of a 61-year old male AML M6 patient with trisomy 8 using PCR-STR with a TH01 locus on 11p15 and fluorescence in situ hybridization (FISH) analysis specific for alpha satellite DNA on chromosome 8. Ten months after HSCT, FISH analysis showed 24.8% recipient cells, but PCR-STR demonstrated 100% donor type chimerism. Further XY FISH analysis of May-Grünwald-Giemsa-stained bone marrow samples clearly demonstrated relapse of the original disease and G-banding analysis of bone marrow samples at relapse showed that an additional chromosomal abnormality, del(11) (p10), had deleted the PCR-STR detection site in all recipient type cells. As such, clinicians should consider the possibility that unexpected karyotype changes may invalidate PCR-STR analysis findings, especially when conflicting results appear among chimerism analyses.