AML mainly; rarely observed in myelodysplastic syndroms (MDS) ormyeloproliferative disorders; biphenotypic T-lymphoid / myeloid leukemiascases have also been described

AML: M1, M2, M4, M6 FAB subtypes; pluripotentstem cell probably involved; there is a trilineage myelodysplasia; sixpatients (4 M1, 1 M2 and 1 T-ALL) from two reports have been described withdel(9q) and CD34+, CD7+, T lymphoid / myeloid biphenotypic leukemia.

0 to 3% of AML cases, depending on series; both sexes equallyrepresented; adults and children may be affected

frequent sideroblasts; leukemic blasts are agranular,with large vacuoles on Giemsa staining and localized positivity formyeloperoxydase (MPO); giant MPO positive granules are described,corresponding to =AB pseudo-Chediak-Higashi =BB granules; most blast cells areCD34 positive

when del(9q) is the unique chromosome abnormality the prognosis,depending on AML subtype, is variable; (del(9q) as a secondary anomaly int(8;21) has no prognostic consequence for some workers and is a factor ofworse prognosis for others)

interstitial deletion of chromosome 9 long arm,called del(9q) or 9q-, involving a variable chromosome segment; the region9q21-22 seems constantly involved

this constantly deleted region has not yet been moreprecisely defined and it is not known whether deletion of one or morecritical gene(s) are be involved. Thus there are presently no 9q molecularprobes availaible to assess 9q deletion

on 31 reviewed cases of AML with del(9q) as a primarychange, none had additional anomaliesdel(9q) as a secondary anomaly:- association with t(8 ;21) represents the majority of cases; t(8 ;21)occurs in 5 to 10 % of patients with AML, and its association with del(9q)is the second more frequent, after the association with loss of one sexchromosome; it represents approximatly 10-15 % of cases- association with t(15 ;17), in promyelocytic leukemia, has also seldom(1%) been observed- in these two syndromes, del(9q) is usually not present at diagnosis butappears as an additional change at relapse- del(9q) has never been described in association with other recurrentprimary changes

unbalanced translocations involving 9q may, in a way, be considered as del(9q) variants.

del(9q) as the sole abnormality must be distinguished fromsyndromes where it is associated with other chromosome rearrangements; inparticular, there is frequent association with LAM2 expressingt(8;21)(q22;q22), and, also, with t(15;17)(q24;q21);we herein describe del(9q) as the sole anomaly, when not otherwise specified