Leukaemia cytogenetics / H. Jackson Woodliff.

  • Woodliff, H. Jackson.
Date:
1971
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Leukaemia cytogenetics / H. Jackson Woodliff. Source: Wellcome Collection.

    64/168 (page 48)
    Chapter VI CHRONIC GRANULOCYTIC LEUKAEMIA Introduction The report by Nowell and Hungerford (1960a, b, and c) of a characteristic minute chromosome in chronic granulocytic leukae¬ mia and the rapid confirmation of this finding by the Edinburgh group (Baikie et al, 1960) led to extensive studies in other centres. Called the Philadelphia chromosome (Ph^) after the city in which it was first described (Tough et al., 1961) it is the only abnormal chromosome exempted, for historical reasons, from the rules of nomenclature laid down by the Chicago Conference (1966). Since there will be no Ph^ the chromosome will be abbreviated here to Ph. It is a small acrocentric chromosome which has lost about half the substance of its long arm; the amount deleted varies but is similar in cells from the same patient (Fig. 15). It belongs to the G group and is considered to be one of pair 21 since in good preparations of cells containing Ph^ chromosome two of the three normal small acrocentrics are appreciably smaller than the remaining one (Court Brown and Tough, 1963). The additional chromosome found in Down's syndrome is also thought to be a 21 (Ford and Wollam, 1968). Where visible, the satellites are said to occur more often and appear slightly larger on pair 21 than on pair 22 and their occasional presence on the Ph chromosome sup¬ ports the view that it is a 21. Attempts to settle the question by radioisotope uptake studies have been indefinite; some authors have found that the Ph chromosome belongs to the late replicating pair, others have found an inconsistent pattern (Schmid, 1963; Haines, 1965; Sofuni et al, 1967; Goh, 1968e). The identification of the small acrocentric chromosomes and their relationship to the Ph, the extra G chromosome in mongolism and the deleted G chromosome in some cases of chronic lymphocytic leukaemia (see p. 76) is the subject of continuing studies. In literature to the end of 1963, most but not all, cases of chronic granulocytic leukae¬ mia reported were Ph positive (Table IV). In our laboratory, the Ph chromosome has been present in all cases and we have been