[Identification of marker chromosomes and complex chromosomal translocations, using non radioactive in situ hybridization, in malignant hemopathies]

We describe five patients with hematological malignancies in which fluorescence in situ hybridization technique (FISH) has been combined with classical cytogenetic study for characterizing chromosomal abnormalities. Three of them were chromosome Philadelphia positive; using a 22 chromosome painting probe it was confirmed the presence or absence of a variant complex translocation. In patients 4 and 5, the karyotype showed a marker chromosome which was definitively identified by FISH as a deletion of X chromosome and a 18 ring chromosome, respectively. The value of this methodology in the cytogenetic diagnosis of hematological malignancies is commented.

[Correlation between cellular and cytogenetic morphology using fluorescence in situ hybridization in the study of malignant hemopathies]

The in situ hybridization technique (ISH), using specific chromosome DNA probes on stained bone marrow or peripheral blood smears, allow us to correlate morphological findings with the cytogenetic abnormalities detected by conventional cytogenetic analysis. We have applied this methodology to study three patients, two of them diagnosed of acute lymphoblastic leukaemia (ALL) and one with a myeloid blast crisis of chronic myeloid leukaemia (BC-CML). Conventional cytogenetic analysis showed, among other chromosomal abnormalities, a trisomy 8 in two cases and a trisomy 7 in one case. ISH demonstrated that cytogenetic clonality was restricted to the lymphoblasts in both cases with ALL. In the BC-CML patient, myeloid blasts as well as mature and semimature granulocytic elements showed three hybridization signals. ISH correlating morphological and cytogenetic findings may be a useful technique for lineage as well as for the follow-up of the haematological patients.

The deoxyuridine suppression test in peripheral lymphocytes

The effects of different deoxyuridine (dU) concentrations on lymphocytes stimulated with phytohemagglutinin (PHA) were studied for use in a lymphocyte dU suppression test (L-dUST). High concentrations of dU were necessary to overcome the unspecific spontaneous pattern of folate deficiency, dU suppression tests with cells of bone marrow (BM-dUST) and with lymphocytes were carried out in 15 patients with vitamin B-12 deficiency, in 12 with folate deficiency, and in 10 with other pathological conditions. L-dUST was also carried out in 15 healthy reference controls. The BM-dUST was able to distinguish patients with vitamin B-12 or folate acid deficiencies from those without, while the L-dUST was unable to do so in most cases. L-dUST does not, therefore, appear to be a reliable method for the diagnosis of megaloblastic changes.