“…The most common trisomies reported in myeloid neoplasia are 8, 9, 12 and 21 (Heim & Mitelman, 1986). Of these, only trisomy 21 is associated with myeloid malignancy both as a congenital (Krivit & Good, 1957;Miller et al, 1961;Lin et al, 1980;Lazarus et al, 1981;Morgan et al, 1985;Hayashi et al, 1988) or acquired (Heim & Mitelman, 1986;Knapp et al, 1985;Gold et al, 1983) abnormality. The most simplistic hypothesis relating neoplasm and trisomy would be a dosage effect relating to the presence of a higher copy number of genes potentially relevant to proliferation (Heim & Mitelman, 1986).…”