Absence of allelic loss on chromosome 5q by RFLP analysis in preleukemia.

Thirty-eight patients with various forms of myelodysplastic syndrome (MDS) were studied for the loss of restriction fragment length polymorphism (RFLP) heterozygosity on chromosome 5q as inferential support for the presence of a growth regulatory locus in this area of the genome. Conventional chromosomal analysis was performed in addition to RFLP studies of constitutive and granulocyte DNA using five polymorphisms from chromosome 5. Allelic loss in granulocyte DNA was identified in only one patient in whom monosomy 5 had already been defined cytogenetically. These results suggest that DNA sequence loss from chromosome 5q other than that observed cytogenetically is a rare event in MDS. Thus the potential involvement of a growth regulatory gene(s), from this area of the genome, in the leukemogenic process most likely involves a more subtle genetic change.