Molecular definition of a narrow interval at 7q22.1 associated with myelodysplasia

Chromosome 7 translocations, deletions, or monosomy are associated with myelodysplasia (MDS) and acute myeloid leukemia both in children and adults. These chromosomal anomalies represent one of the most common cytogenetic abnormalities associated with these diseases and usually herald a poor prognosis. In this study two cosmid DNA probes that mapped to 7q22.1 and were known to be separated by approximately 500 kb were identified to flank the proximal inversion breakpoint in a patient carrying a constitutional inversion (7q22.1-34) associated with MDS. A yeast artificial chromosome (YAC) clone that encompassed the two cosmids was identified and shown to span the breakpoint. Fluorescence in situ hybridization was then used to analyze six additional patients with myelodysplasia and chromosomal rearrangements of the 7q22 region (three patients had translocations and three carried deletions). The breakpoint in one of the patients was found to be contained within the same YAC clone that spanned the inversion breakpoint. Moreover, this same interval was determined to be absent in all three patients with chromosomal deletions. These results suggest that this segment of DNA on chromosome 7q22.1 may contain specific gene(s) that have a significant role in myeloid malignancies.     

In vivo administration of recombinant human granulocyte/macrophage colony-stimulating factor in acute lymphoblastic leukemia patients receiving purged autografts [see comments]

Based on the recent reports that recombinant human granulocyte/macrophage colony-stimulating factor (rhGM-CSF) accelerates the rate of engraftment in a variety of autologous bone marrow transplantation settings, we have investigated its effects on hematopoietic recovery of patients with acute lymphoblastic leukemia (ALL) undergoing autologous bone marrow transplantation. Our studies, which involved 25 autologous ALL recipients who received rhGM-CSF and 27 controls similar for disease status (remission or relapse) and disease type (B- or T-lineage) differed from previous studies in one important aspect: the bone marrows were purged with 4- hydroperoxcyclophosphamide (4HC) and anti-T or anti-B-cell lineage- specific antibodies before transplantation. Such treatments frequently lead to a reduction in the CFU-GM content of the transplanted marrow. Eighteen of 25 patients completed the entire course of rhGM-CSF. Of the 16 patients who received greater than or equal to 64 micrograms/M2/d for at least eight days, there were five patients who had an apparent rhGM-CSF response and 11 patients who did not respond. Of the parameters analyzed, only the number of CFU-GM progenitor cells infused per kilogram was significantly associated with an rhGM-CSF response. All patients receiving greater than or equal to 1.2 x 10(4) CFU-GM progenitors per kilogram achieved an absolute neutrophil count (ANC) greater than or equal to 1,000/microL by day 21 and had a greater than 50% decrement in ANC within 48 to 72 hours of discontinuing rhGM-CSF, as contrasted to none of the patients receiving less than or equal to 7.2 x 10(3) CFU-GM progenitors per kilogram.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemoglobin Ohio (beta 142 Ala replaced by): a new abnormal hemoglobin with high oxygen affinity and erythrocytosis

Hemoglobin Ohio [beta 142 (H20) Ala replaced by Asp] was found in three members of a white family, all of whom showed erythrocytosis. The variant hemoglobin has a high oxygen affinity, a reduced Bohr effect, and diminished cooperativity. The functional abnormalities of Hb Ohio are explained by the proximity of the substituent beta 142 residue, both to beta 143 His, which is involved in the DPG binding site of hemoglobin, and to the critical C terminal region of the beta chain, which participates in the stabilization of the deoxy (T) conformation.