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Cytogenetic studies of acute myeloid leukaemias reveal non-random chromosomal abnormalities in 50–70% of karyotypes. Some are correlated with morphological and immunological parameters and constitute a prognostic factor independent of the other factors of risk: favourable for acute leukaemias myeloid with translocations t(8 ;21), t(15 ;17) and inversion or translocation of the chromosome 16, inv(16)/t(16 ;16), poor with deletion of the long arm of chromosome 5 del(5q), rearrangement of the 11q23 region and complex karyotypes. The distribution of the anomalies depends on the age: 11q23 and t(8;21) more frequent for the child, del(5q) and complex anomalies more frequent for the adult.The karyotypes are essential for the diagnosis, the follow-up of the patients and the evaluation of the relapse. It plays a fundamental part in the detection of new genes and their partners implied in the leucemogenese. The knowledge of their function is essential to open new therapeutic ways. [Copyright &y& Elsevier]

Cytogenetic study reveals non random chromosomal abnormalities in 50-80% of patients with acute leukemia. These changes are correlated with morphological [t(15;17) closely connected with FAB M3] and (or) immunological findings [t(1;19) with pre-B/early pre-B ALL]. Karyotype in ALL is an independent prognostic factor. Patients with ALL and hyperdiploidy > 50 chromosomes fared the best as well as patients with AML and inv(16). Conversely the Philadelphia chromosome or t(4;11) in ALL, del5q or trisomy 8 in AML have shown an adverse predictive value. Cytogenetic study is a useful tool to detect relapse and residual disease. Cytogenetic abnormalities have also provided focus for molecular studies of leukemogenesis.

A review on the association between acute leukemias (AL) and constitutional chromosome abnormalities (CCA) is presented. AL, myeloblastic or lymphoblastic according to age are 18 to 20 times more frequent in Down Syndrome (DS) children than in non DS children. The incidence of acquired chromosome abnormalities is similar in leukemic cells of DS and non DS patients but the type of anomalies, in the leukemic myeloblastic cells of DS, are different : hyperdiploidy, excess of C, F and G. Gain of chromosomes 8, 19 and 22 would characterize leukemic myeloblasts in an early stage of differentiation. Recent data on transient leukemoid reactions show that a 21 in DS appears to be predisposing factor in the development of AL. Association between AL and other balanced or unbalanced CCA appears until now to be fortuitous.

A review on the association between acute leukemias (AL) and constitutional chromosome abnormalities (CCA) is presented. AL, myeloblastic or lymphoblastic according to age are 16 to 20 times more frequent in Down Syndrome (DS) children than in non DS children. The incidence of acquired chromosome abnormalities is similar in leukemic cells of DS and non DS patients but the type of anomalies, in the leukemic myeloblastic cells of DS, are different: hyperdiploidy, excess of C, F and G. Gain of chromosomes 8, 19 and 22 would characterize leukemic myeloblasts in an early stage of differentiation. Recent data on transient leukemoid reactions show that a 21 in DS appears to be predisposing factor in the development of AL. Association between AL and other balanced or unbalanced CCA appears until now to be fortuitous.

A t(X; Y) was discovered in 32 year-old female patient who has had three consecutive miscarriages. Molecular analysis of the loci DXS 31 and DYS 22 was performed which confirmed and precise the breakpoints at Xp22.3 and Yq11. Genetic counselling was based upon the accurate definition of the chromosome rearrangement and the analysis of the outcomes of similar published observations.

Using immunocytological techniques, neuroectodermal markers were identified on Ewing's sarcoma cell lines established in vitro and carrying the chromosomal translocation t(11;22). Eight cell lines were tested using a panel of monoclonal antibodies. The presence of cell surface antigens recognized by HNK-1 antibody was confirmed. The cells showed also positive reactions using antibodies directed against Neuron-Specific-Enolase and neurofilament proteins. The presence of these neural markers in the Ewing's sarcoma cells tested is an additional argument substantiating the putative neural origin of this tumor.

We report a de novo double reciprocal translocation, involving three chromosomes in a 25 year-old female patient, who has had twelve miscarriages.

Among number of women having consulted for repeated miscarriages about sixty have a gonosomic mosaicism involving chromosome X for which abnormal clones (monosomy and/or excess) are always the minority. A retrospective study of the obstetrical follow up these patients have shown that 23% of them will give birth to a child with a chromosomic abnormality (21 trisomy, 13 trisomy, 45,X, 45,X/46,X iso X (q), 48,XXXX, 49 XXXXXY, del 5 p-). The hypothesis of a tendency toward non-disjunction is pushing for an prenatal diagnosis for patients with X mosaicism. However one can question about the real meaning of this abnormality regarding to the fact that the patients referred are not representative of the general population. Should interchromosomic interaction be taken for responsible? Is the risk for having a child chromosomic abnormality, especially X aneuploidy the same than for the overall population. It certainly would be rewarding to look after these different hypothesis in a multicentric collaborative study.