title: Human gamma-chain genes are rearranged in leukaemic T cells and map to the short arm of chromosome 7.
abstract: Three gene families that rearrange during the somatic development of T cells have been identified in the murine genome. Two of these gene families (alpha and beta) encode subunits of the antigen-specific T-cell receptor and are also present in the human genome. The third gene family, designated here as the gamma-chain gene family, is rearranged in murine cytolytic T cells but not in most helper T cells. Here we present evidence that the human genome also contains gamma-chain genes that undergo somatic rearrangement in leukaemia-derived T cells. Murine gamma-chain genes appear to be encoded in gene segments that are analogous to the immunoglobulin gene variable, constant and joining segments. There are two closely related constant-region gene segments in the human genome. One of the constant-region genes is deleted in all three T-cell leukaemias that we have studied. The two constant-region gamma-chain genes reside on the short arm of chromosome 7 (7p15); this region is involved in chromosomal rearrangements identified in T cells from individuals with the immunodeficiency syndrome ataxia telangiectasia and observed only rarely in routine cytogenetic analyses of normal individuals. This region is also a secondary site of beta-chain gene hybridization.
mesh_terms: D000595:Amino Acid Sequence; D001260:Ataxia Telangiectasia / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D002874:Chromosome Mapping; D002906:Chromosomes, Human, 6-12 and X; D004247:DNA / Q000235:genetics; D005796:Genes; D006801:Humans; D007938:Leukemia / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D011995:Recombination, Genetic; D013601:T-Lymphocytes / Q000502:physiology*; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology
chemical_list: D009363:Neoplasm Proteins; D004247:DNA