Biallelic Loss of 7q34 () and 9p21.3 (/) in Adult Ph-Negative Acute T-Lymphoblastic Leukemia.

Tumor cells of acute lymphoblastic leukemia (ALL) may have various genetic abnormalities. Some of them lead to a complete loss of certain genes. Our aim was to reveal biallelic deletions of genes in Ph-negative T-ALL. Chromosomal microarray analysis (CMA) was performed for 47 patients with de novo Ph-negative T-ALL, who received treatment according to RALL-2016m clinical protocol at the National Medical Research Center for Hematology (Moscow, Russia) from 2017 to 2023. Out of forty-seven patients, only three had normal molecular karyotype. The other 44 patients had multiple gains, losses, and copy neutral losses of heterozygosity. Biallelic losses were found in 14 patients (30%). In ten patients (21%), a biallelic deletion of 9p21.3 involved a different number of genes, however gene loss was noted in all ten cases. For seven patients (15%), a biallelic deletion of 7q34 was found, including two genes-, located within the T-cell receptor beta () locus. A clonal rearrangement of the gene was revealed in 6 out of 7 cases with 7q34 biallelic loss. Both biallelic deletions can be considered favorable prognostic factors, with an association with 9p21 being statistically significant ( = 0.01) and a trend for 7q34 ( = 0.12) being observed.