Open AccessIncreased Rate of Spontaneous Mitotic Recombination in T Lymphocytes from a Bloom's Syndrome Patient Using a Flow‐cytometric Assay at HLA‐A Locus
Author(s) -
Kusunoki Yoichiro,
Hayashi Tomonori,
Hirai Yuko,
Kushiro Junichi,
Tatsumi Kouichi,
Kurihara Takayuki,
Zghal Mohamed,
Kamoun Mohamed R.,
Takebe Hiraku,
Jeffreys Alec,
Nakamura Nori,
Akiyama Mitoshi
Publication year - 1994
Publication title -
japanese journal of cancer research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 0910-5050
DOI - 10.1111/j.1349-7006.1994.tb02403.x
Subject(s) - bloom syndrome , human leukocyte antigen , locus (genetics) , mitotic crossover , flow cytometry , bloom , biology , mitosis , immunology , genetics , recombination , microbiology and biotechnology , antigen , gene , helicase , rna , ecology
Bloom's syndrome (BS) is an autosomal recessive disorder conferring high propensity for cancer and displaying a high degree of genetic instability; the frequency of sister chromatid exchange is characteristically 10 times above background. The symmetrical four‐armed chromatid interchanges are much more readily detected in peripheral blood lymphocytes of BS patients, suggesting that the frequency of somatic recombination is also increased. In the present study, the rate of spontaneous loss of HLA‐A allele expression was estimated following fluctuation analysis in cultured T lymphocytes using a flow‐cytometric assay. It was found to be 10 times or more higher than normal in lymphocytes from a BS patient. Molecular and chromosome analyses showed that all 13 independent variants from the patient were most likely derived from somatic recombinations. Further tests for loss of heterozygosity at a closely linked proximal locus, HLA‐DQA1 , showed that as many as half of the recombinants retained heterozygosity irrespective of the donor. The results suggest that the HLA region is hyperrecombinogenic in somatic cells and that the elevated recombination rate in BS cells results from the general increase at ordinary sites and not from random creation of unusual sites for recombination.