The human GRAF gene is fused to MLL in a unique t(5;11)(q31;q23) and both alleles are disrupted in three cases of myelodysplastic syndrome/acute myeloid leukemia with a deletion 5q

The human GRAF gene is fused to MLL in a unique t(5;11)(q31;q23) and both alleles are disrupted in three cases of myelodysplastic syndrome/acute myeloid leukemia with a deletion 5q

Departments of ^*General Pediatrics, Hematology, and Oncology, and ^§Pathology, University of Giessen, D-35392-Giessen, Germany; ^‡Children's Cancer Research Institute and Ludwig Boltzmann Institute for Cytogenetic Diagnosis, St. Anna Kinderspital, 1090, Vienna, Austria; and ^¶Department of Medicine I, Division of Hematology and Hemostaseology, University of Vienna, 1090, Vienna, Austria

Edited by Janet D. Rowley, The University of Chicago Medical Center, Chicago, IL, and approved May 15, 2000 (received for review February 24, 2000)

Abstract

We have isolated the human GRAF gene (for GTPase regulator associated with the focal adhesion kinase pp125^FAK). This gene was fused with MLL in a unique t(5;11)(q31;q23) that occurred in an infant with juvenile myelomonocytic leukemia. GRAF encodes a member of the Rho family of the GTPase-activating protein (GAP) family. On the protein level, it is 90% homologous to the recently described chicken GRAF gene that functions as a GAP of RhoA in vivo and is thus a critical component of the integrin signaling transduction pathway. The particular position of the human GRAF gene at 5q31 and the proposed antiproliferative and tumor suppressor properties of its avian homologue suggest that it also might be pathogenetically relevant for hematologic malignancies with deletions of 5q. To investigate this possibility, we sequenced 4–5 individual cDNA clones from 13 cases in which one allele of GRAF was deleted. We found point mutations within the GAP domain of the second GRAF allele in one patient. In two additional patients we found an insertion of 52 or 74 bp within the GRAF cDNA that generates a reading frame shift followed by a premature stop codon. GRAF maps outside the previously defined commonly deleted 5q31 region. Nevertheless, inactivation of both alleles in at least some cases suggests that deletions and mutations of the GRAF gene may be instrumental in the development and progression of hematopoeitic disorders with a del(5q).

Footnotes

↵ † A.B. and S.B. contributed equally to this work.
↵ ‖ To whom reprint requests should be addressed. E-mail: Fritz.H.Lampert{at}paediat.med.uni-giessen.de.
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: The sequence reported in this paper has been deposited in the GenBank database (accession no. Y10388).
Article published online before print: Proc. Natl. Acad. Sci. USA, 10.1073/pnas.150079597.
Article and publication date are at www.pnas.org/cgi/doi/10.1073/pnas.150079597
Abbreviations:

GRAF,

GTPase regulator associated with the focal adhesion kinase pp125FAK;

MLL,

mixed-lineage leukemia;

RT-PCR,

reverse transcription–PCR;

MDS,

myelodysplastic syndrome;

AML,

acute myeloid leukemia;

GAP,

GTPase-activating protein;

RACE,

rapid amplification of cDNA ends;

FISH,

fluorescence in situ hybridization;

SH3,

Src homology 3;

BCR,

breakpoint cluster region