Image by Spencer Phillips
DNA helix
New research has revealed a link between rare gene variants and survival after hematopoietic stem cell transplant (HSCT).
Researchers performed exome sequencing in nearly 2500 HSCT recipients and their matched, unrelated donors.
The sequencing revealed several gene variants—in both donors and recipients—that were significantly associated with overall survival (OS), transplant-related mortality (TRM), and disease-related mortality (DRM) after HSCT.
Qianqian Zhu, PhD, of Roswell Park Comprehensive Cancer Center in Buffalo, New York, and her colleagues described these findings in Blood.
The team performed exome sequencing—using the Illumina HumanExome BeadChip—in patients who participated in the DISCOVeRY-BMT study.
This included 2473 HSCT recipients who had acute myeloid leukemia, acute lymphoblastic leukemia, or myelodysplastic syndromes. It also included 2221 donors who were a 10/10 human leukocyte antigen match for each recipient.
The researchers looked at genetic variants in donors and recipients and assessed the variants’ associations with OS, TRM, and DRM.
Variants in recipients
Analyses revealed an increased risk of TRM when there was a mismatch between donors and recipients for a variant in TEX38—rs200092801. The increased risk was even more pronounced when either the recipient or the donor was female.
Among the recipients mismatched with their donors at rs200092801, every female recipient and every recipient with a female donor died from TRM. In comparison, 44% of the male recipients with male donors died from TRM.
The researchers said the rs200092801 variant may prompt the production of a mutant peptide that can be presented by MHC-I molecules to immune cells to trigger downstream immune response and TRM.
Dr Zhu and her colleagues also identified variants that appeared to have a positive impact on TRM and OS.
Recipients who had any of 6 variants in the gene OR51D1 had a decreased risk of TRM and improved OS.
The variants (rs138224979, rs148606808, rs141786655, rs61745314, rs200394876, and rs149135276) were not associated with DRM, so the researchers concluded that the improvement in OS was driven by protection against TRM.
Donor variants linked to OS
Donors had variants in 4 genes—ALPP, EMID1, SLC44A5, and LRP1—that were associated with OS but not TRM or DRM.
The 3 variants identified in ALPP (rs144454460, rs140078460, and rs142493383) were associated with improved OS.
And the 2 variants in SLC44A5 (rs143004355 and rs149696907) were associated with worse OS.
There were 2 variants in EMID1. One was associated with improved OS (rs34772704), and the other was associated with decreased OS (rs139996840).
And there were 27 variants in LRP1. Some had a positive association with OS, and others had a negative association.
Donor variants linked to TRM and DRM
Six variants in the HHAT gene were associated with TRM. Five of the variants appeared to have a protective effect against TRM (rs145455128, rs146916002, rs61744143, rs149597734, and rs145943928). For the other variant (rs141591165), the apparent effect was inconsistent between patient cohorts.
There were 3 variants in LYZL4 associated with DRM. Two were associated with an increased risk of DRM (rs147770623 and rs76947105), and 1 appeared to have a protective effect (rs181886204).
Six variants in NT5E appeared to have a protective effect against DRM (rs200250022, rs200369370, rs41271617, rs200648774, rs144719925, and rs145505137).
The researchers said the variants in NT5E probably reduce the enzyme activity of the gene. This supports preclinical findings showing that targeted blockade of NT5E can slow tumor growth.
“We have just started to uncover the biological relevance of these new and unexpected genes to a patient’s survival after [HSCT],” Dr Zhu said.
“Our findings shed light on new areas that were not considered before, but we need to further replicate and test our findings. We’re hoping that additional studies of this type will continue to discover novel genes leading to improved outcomes for patients.”