Copy Number Loss at Chromosome 14q11.2 Correlates With the Proportion of T Cells in Biopsies and Helps Identify T-Cell Neoplasms

Context.— Evidence of T-cell clonality is often critical in supporting a T-cell lymphoma. Objectives.— To retrospectively explore the significance of copy number losses at the 14q11.2 T-cell receptor α locus in relation to the presence of a T-cell neoplasm and proportion of T cells by targeted next-generation sequencing. Design.— Targeted next-generation sequencing data from 139 tissue biopsies including T-cell lymphomas, B-cell lymphomas, classic Hodgkin lymphomas, nonhematopoietic malignancies, and normal samples were reviewed for copy number losses involving the T-cell receptor α gene segments at chr14q11.2. Results.— We found that biallelic or homozygous deletion of 14q11.2 was found in most (28 of 33, 84.8%) T-cell lymphomas. The magnitude of 14q11.2 loss showed a statistically significant correlation with the proportion of T cells in lymphoma tissue samples. Copy number losses could also be detected in other lymphomas with high number of T cells (8 of 32, 25% of B-cell lymphomas, 4 of 4 classical Hodgkin lymphomas), though biallelic/homozygous deletion of 14q11.2 was not significantly observed outside of T-cell lymphomas. Most nonhematopoietic neoplasms and normal tissues (59 of 64, 92.2%) showed no significant copy number losses involving the T-cell receptor α locus at chr14q11.2. Conclusions.— Analysis of copy number losses at the T-cell receptor α locus chr14q11.2 with targeted next-generation sequencing can potentially be used to estimate the proportion of T cells and detect T-cell neoplasms.