Evidence for the clonal origin of chronic myeloid leukemia from a sex chromosome mosaic: clinical, cytogenetic, and marrow culture studies

Cytogenetic studies on a 7--yr-oId child pre-senting with clinical and hematological fea-tures of chronic myeloid leukemia (CML) re-vealed a constitutional 46 XV/47 XVV mosaicism in skin, blood, and marrow. A third 46 XV, Ph1 cell line predominated in the marrow on initial presentation and in subsequent acute transformation. Assessment of granulocytic colony-forming capacity in agar culture revealed that colony-forming cells (CFCs) were greatly increased in the circulation and possessed the abnormal light buoyant density and low susceptibility to tritiated thy-midine killing which distinguishes leukemic CFCs from normal. During acute transforma