Deletion Of The Long Arm Of Chromosome

Del (20q) carries a favorable prognosis as an isolated abnormality. It is more often seen in early MDS. Prominent erythrocytic and megakaryocytic dysplasia is often seen. Mature granulocytes from the peripheral blood may lack the abnormality, suggesting an increased propensity for apoptosis in the clone carrying this abnormality.3134 Isochromosome 20q with loss of interstitial material i (20q-) was described recently in six MDS patients out of a registry of 998. This was seen more commonly in older patients, whose MDS behaved different clinically from the 20q-syndrome, with its rapid progression and shorter survival. The i (20q-) could represent a further evolution of the 20q karyotype, thus predicting disease progres-sion.36

11q23 SYNDROME

Translocations involving 11q23 are classically described in therapy-related MDS secondary to topoi-somerase II class drugs.37 38 The MLL (mixed lineage leukemia) gene is located on 11q23, and in acute leukemia usually portends a poor prognosis. The exact involvement of the MLL gene in primary MDS is not well defined.34

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