Gurer, Ekin EceOguz, Fatma S. A. V. R. A. N.Kalayoglu, Sevgi BEsIsIK.Aktas, ZerrinGulbas, ZaferOncul, Mustafa OralSezerman, Ugur2023-02-212023-02-212022-01-0110.26650/IUITFD.1027106https://hdl.handle.net/11443/1680http://dx.doi.org/10.26650/IUITFD.1027106Objective: In our study, we analyzed gut microbiota in allo-HSCT patients and aimed to evaluate the relationship of gut microbio-ta with transplant complications, mainly GVHD. Materials and Methods: A total of 25 adult recipients and do-nors who underwent allo-HSCT at Istanbul Anadolu Medical Center were included in the study. Stool samples were collected twice, before chemotherapy regimen and after allo-HSCT. Sam-ples were analyzed by High Melting (HRM) Analysis and Next Generation Sequencing (NGS) methods after nucleic acid iso-lation. Sequencing was done with Illumina MiSeq. Bacteria Silva database was used for taxonomic classification and QIIME 2 pro-grams were used for analysis. Statistical analyses were carried out with the R statistical programming language. Results: Twenty-five allo-HKHN recipients were included in the study. The mean age was 46.24 +/- 14.86 years in recipients and 43.40 +/- 13.20 years in donors. Gender distribution was M/F: 15/10 in patients and M/F: 17/8 in donors. Recipient and donor sib-ling HLA match was 10/10. The rate of GVHD associated with Allo-HSCT was 16\%, and the relapse rate was 16\%. It was ob-served that the Firmicutes and Proteobacteria phyla changed significantly before and after transplantation. The number of Entereccocus species was found to be higher in patients who developed GVHD and died. The loss of diversity was found to be statistically significant in the pre-transplant and post-engraft-ment samples of the patients. Conclusion: Gut microbiota diversity may guide the monitoring of GVHD and also may be manipulated for the treatment of GVHD. It is thought that increasing the diversity of commensal bacteria can also positively affect the prognosis of the disease.intestinal microbiotablood diseaseshematopoietic stem cell transplantationHLAArticleWOS:000811547500001