Delineation of a minimal interval and identification of 9 candidates for atumor suppressor gene in malignant myeloid disorders on 5q31

Interstitial deletion or loss of chromosome 5 is frequent in malignant myel oid disorders, including myelodysplasia (MDS) and acute myeloid leukemia (A ML), suggesting the presence of a tumor suppressor gene. Loss of heterozygo sity (LOH) analysis was used to define a minimal deletion interval for this gene. Polymorphic markers on 5q31 were identified using a high-resolution physical and radiation hybrid breakpoint map and applied to a patient with AML with a subcytogenetic deletion of 5q, By comparing the DNA from leukemi c cells to buccal mucosa cells, LOH was detected with markers D5S476 and D5 S1372 with retention of flanking markers D5S500 to D5S594. The D5S500-D5S59 4 interval, which covers approximately 700 kb, thus represents a minimal lo calization for the tumor suppressor gene. Further refinement of the physica l map enabled the specification of 9 transcription units within the encompa ssing radiation hybrid bins and 7 in flanking bins. The 9 candidates includ e genes CDC25, HSPA9, EGR1, CTNNA1, and 5 unknown ESTs, Reverse-transcripti on polymerase chain reaction confirms that all of them are expressed in nor mal human bone marrow CD34(+) cells and in AML cell lines and thus represen t likely candidates for the MDS-AML tumor suppressor gene at 5q31.(Blood.20 00;95:2372-2377) (C) 2000 by The American Society of Hematology.