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May 16, 1990


JAMA. 1990;263(19):2671-2672. doi:10.1001/jama.1990.03440190127068

In keeping with the inevitable wave of changes experienced by medicine each year, several developing technologies in the field of pathology are particularly noteworthy.

In hematopathology, recombinant DNA technology has provided a tool that increases our understanding of disease and enhances diagnostic capabilities. The rearrangement of the immunoglobulin genes and T-cell receptor genes by differentiating lymphocytes reveals an intricate process that is helping us understand neoplasia.1 Early hematopoietic progenitor cells begin lymphoid differentiation by rearranging the δ-chain gene of the T-cell receptor. If this rearrangement produces a DNA sequence without a triplet stop codon for termination of transcription through the gene (a so-called open reading frame), the cell will bear γ/δ-chain dimers and become a CD3+ CD4- CD8- natural killer/cytotoxic lymphocyte. δ-Chain rearrangement usually fails; then the lymphocyte attempts an α-chain rearrangement. The α-chain gene surrounds the δ-chain DNA sequences and an α-chain rearrangement results in permanent deletion of