See Acute myeloid leukemia
See Chronic lymphocytic leukemia (CLL)

Most of the AML patients were male and most over age 40 at diagnosis.

Some of the patients achieved complete remission, with survival ranging from 30+ months to 54+ months. Other patients succumbed to their disease in 2-13 months.

Four cases of CLL have been reported, with 15-41% of metaphase cells exhibiting monosomy 21 as a sole cytogenetic abnormality. Most cases were staged A/O in the Binet/Rai classification.

All five cases were males aged 45-77 years

One CLL patient exhibited a 13q deletion by FISH that was not observed in the metaphase analysis.

Survival was 77 months and 90+ months in the two cases where information was provided.

True monosomy 21 mosaicism can appear as the sole cytogenetic abnormality but it is rare. Many of the reported cases in the literature probably represent technical artifacts due to random loss of chromosome 21 in multiple cells by chance alone. Suspected monosomy 21 mosaicism should be confirmed by analysis of additional metaphase cells and by FISH analysis of interphase cells. Of the reported cases that are most likely to represent true clonal disease, Acute myeloid leukemia (AML) and chronic myelogenous leukemia (CML) were the most common diagnoses, with one case each of myelodyplasia (MDS), MDS/MPD (myelodysplastic syndrome), acute lymphocytic leukemia (ALL), and multiple myeloma .