E. Kleihauer

C-abl and bcr are rearranged in a Ph1-negative CML patient.

Chromosomal analysis of a patient with chronic myelocytic leukemia (CML) revealed a translocation (9;12) (q34;q21) without a detectable Philadelphia chromosome (Ph1). Using molecular approaches we demonstrate (i) a rearrangement within the CML breakpoint cluster region (bcr) on chromosome 22, and (ii) a joint translocation of bcr and c‐abl oncogene sequences to the derivative chromosome 12. These observations support the view that sequences residing on both chromosome 9 (c‐abl) and 22 (bcr) are involved in the generation of CML and suggest that a subset of Ph1‐negative patients may in fact belong to the clinical entity of Ph1‐positive CML.

Rapid and non-radioactive prenatal diagnosis of β thalassaemia and sickle cell disease: application of the polymerase chain reaction (PCR)

The standard method for the prenatal diagnosis of the haemoglobinopathies is by restriction enzyme mapping of chorionic villus DNA using Southern blotting and radioactively labelled gene probes. An improvement of the procedure which involves the selective amplification of DNA fragments by the polymerase chain reaction allows one to visualize restriction fragments directly without the use of radioactivity and within 2 d after obtaining the sample.

Additional c-abl/bcr rearrangements in a CML patient exhibiting two Ph1 chromosomes during blast crisis

Recent data suggest that two human genes, c-abl on chromosome 9 and bcr on chromosome 22, are involved in the generation of Ph1-positive CML. To examine a possible role of these sequences in transition from chronic towards blastic phase, rearrangements within bcr were analysed in 4 patients with Ph1-positive CML during chronic and acute phase. In 3 patients bcr rearrangements were identical in both phases, while in a fourth patient with duplicated Ph1 an amplified additional bcr fragment was detected in acute phase. Northern blot analysis of blast cells of the latter patient showed a novel 10.3 kb RNA species that replaced the altered 8 kb RNA transcript usually found in Ph1-positive CML.

Involvement of chromosome 9 in variant Ph1 translocation

Cytogenetic analysis of a patient with chronic myelocytic leukemia revealed a translocation (21; 22) (q 22; q 11) without a detectable involvement of chromosome 9. By in-situ hybridization studies, however, we demonstrate a reciprocal translocation of sequences from chromosome 9 (c-abl) to Ph1 and chromosome 22 (bcr) to 9, respectively. These observations suggest a consistent participation of chromosome 9 in the Ph1 translocation, regardless of the cytogenetic subtype.

Conversion of acute undifferentiated leukemia phenotypes: analysis of clonal development.

The cellular origin of acute undifferentiated leukemia (AUL) is still a matter of controversy. We report on two cases in which the diagnosis of AUL was established according to restricted criteria. Blast cells of both patients showed phenotypic conversion during the course of disease. In one case, within 24 days from starting treatment, the leukemic phenotype changed from AUL to acute myelomonocytic leukemia (FAB L1, TdT+ to FAB M4, TdT-). The initial phenotype of this acute leukemia was characterized by the co-expression of both B-lymphoid and myeloid markers on the same cell. Moreover, analysis of esterase isoenzyme pattern showed the whole spectrum of isoenzymes typically seen in myelomonocytic leukemias already at diagnosis, yet blast cells additionally contained all three isoenzymes of beta-hexosaminidase typically seen in AUL. However, examination of immunoglobulin (Ig) heavy chain gene rearrangement initially and after conversion revealed an identical monoclonal configuration of Ig heavy chain sequences in both samples. The second AUL patient relapsed after allogeneic bone marrow transplantation with common ALL-antigen (CALLA) positive acute leukemia. Subsequent Southern blot analysis showed a novel rearranged Ig fragment compared to the analysis before transplantation indicating that the leukemic clones prior to and after transplantation were not identical. No chromosomal abnormalities were observed in both cases. These data support the view that AUL cells originate from a pluripotent stem cell that is capable to differentiate in the myelomonocytic lineage (patient 1), and confirm the value of Ig gene analysis as marker for cellular clonality.

DNA restriction mapping identifies the chromosome carrying the mutant Hb Presbyterian β-globin gene

SummaryRestriction endonuclease mapping of cellular DNA has been used to identify chromosomes that carry the mutant Hb Presbyterian β-globin genes in a family with individuals heterozygous for this disease. The presence of the polymorphic Hind III restriction site in the Gγ-globolin gene and its absence in the Aγ-globolin gene were shown to be in phase with the Hb Presbyterian mutation yielding a haplotype constellation that is diagnostic for any further affected offspring.

Thalassemia intermedia: compound heterozygous β∘/β+-thalassemia and co-inherited heterozygous α+-thalassemia

SummaryThe relative excess of α- over β-globin chains in the erythroid precursors is the chief pathophysiological factor of homozygous β-thalassemia. The clinical picture is usually characterized by a transfusion-dependent dyserythropoietic anemia (thalassemia major). However, some patients present with moderate anemia that does not require regular blood transfusions (thalassemia intermedia). The molecular heterogeneity of β-thalassemia mutations and changes of α- and γ-globin gene expression play an important role in modifying the clinical phenotype. We report here on a female Greek patient with homozygous β-thalassemia but normal growth and development, excellent exercise tolerance, and no need of blood transfusions. She is thus mildly affected clinically, although there is marked pallor, jaundice, and hepatosplenomegaly. These signs correspond to her marked hypochromic, microcytic anemia with erythroid hyperplasia of the bone marrow. β-Globin genotyping shows her to be compound heterozygous for the codon 39 C → T β∘-nonsense mutation and for the T → C β+-mutation at position 6 of the splice consensus at the exon 1/intron 1 junction (CD39 C → T/IVS 1–6 T → C). α-Globin gene mapping demonstrates the presence of a 3.7-kb α+-thalassemia deletion on one allele (−α3.7/αα). Taken together, this study identifies a complex interaction of genetic factors that do not significantly alter the clinical phenotype when present alone but ameliorate the course of homozygous β-thalassemia when inherited in combination.

Hemoglobin Kln: Analysis of linkage relationships between the mutant gene and polymorphic restriction sites in the ?-globin gene cluster

SummaryNuclear DNA has been analyzed by means of restriction endonuclease mapping procedure to identify chromosomes that carry mutant Hb Köln β-globin genes in a family with individuals heterozygous for this disease. Inherited DNA polymorphisms within the β-globin gene cluster yielded a direct linkage of the Hb Köln mutation to haplotype constellations that are diagnostic for further off-spring.

Hb M Milwaukee in a German family.

The second occurrence of Hb M Milwaukee is reported in two members of a German family who had cyanosis since early childhood. Contrary to earlier reports, Hb M Milwaukee exhibits a distinct heat instability. It is suggested, that in this family the variant resulted from a new mutation.

Hemoglobin F Koelliker (α2 minus 141 (HC 3) Arg γ2) A Modification of Fetal Hemoglobin

An electrophoretically HbA-like hemoglobin component is produced In increasing amounts during storage in hemolysate preparations from macerated tissue (liver, kidney, spleen) of fetuses. Within twenty four hours after hemolysate preparation the “fast moving” fraction increases up to 40 per cent of total hemoglobin, while the concentration of HbA remains constant (5-7 %) in hemolysates obtained from peripheral blood of the same donor individuals. By structural studies (fingerprint and aminoacid analysis) the HbA-like component was identified as ai. artefact of HbF, characterized by the absence of the C-terminal arginine of the α chains. From experimental data it is concluded, that the break down product results from a digestion of HbF by carboxypeptidase B, the enzyme being released from the macerated tissues. Analogous to a modification of HbA, i.e. Hb Koelliker (α2 minus 141 Arg β2), the structure of the degradaeion product of Hbf is α2 minus 141 Arg γ2 (HbF Koelliker).These findings should be considered...