Cytological and cytogenetic studies of nine acute granulocytic leukemia with t (8; 21) translocation were performed from the same bone marrow and blood cell samples. It was shown that the chromosome abnormality was restricted to leukemic cells and that normal metaphases were erythroblast mitoses. Using cell cultures in which only or mainly leukemic cells were able to divide permits easier detection of chromosomal aberrations. These results led us to postulate an inhibitory role of leukemic cells on the division of normal granulocytic cells.

25 presumably induced leukemias, either following treatment (lymphoma, polycythemia vera, essential thrombocythemia, cancers) or after exposure to oncogenic agents have been studied cytogenetically and cytologically. Complex chromosomal abnormalities were associated with a difficult cytological classification. Complete monosomy 7 with presence of micromegacaryocytes and macroplatelets was observed in 7 cases. The findings observed in induced leukemias were compared with those found in "primitive" leukemias showing the same chromosomal patterns. The same relationships between cytology and cytogenetics have been observed.

Echotomography and a caryotype were carried out on the liquor and at an interval of one week between the two, two series of hormone levels were also carried out on the liquor and on the peripheral venous blood of a molar triploid pregnancy diagnosed clinically. These results have been compared with those that are known to occur in hydatidiform mole, and in other case histories that have been published of embryonic mole. The histological appearance of the fetal gonads resembles that found in Klinefelter's syndrome. The tests carried out on the HLA systems of the parents and of the fetus favours a maternal origin for the extra chromosomal complement.

Observations in two pairs of identical twins illustrate the importance of genetic factors in determining the outcome of exposure to asbestos in relation to pleural plaques and bronchogenic carcinoma. The first pair of twins, laggers with french railroad (S.N.C.F.), were discovered fortuitously, after only several years exposure, to have bilateral pleural plaques and calcification at the same site on the axillary and diaphragmatic surfaces. The second set of twins developed epidermoïd bronchial carcinoma : one at the right hilum, the other postero-basally on the right in 1969 and 1977 respectively. Both were in ship-building and each had been exposed to asbestos in the same yard for 20 years between 1945 and 1965. Radiographs showed left sided pleural calcification and reticular shadowing at the bases in the two cases. These observations show the role of the host in the generation of asbestos disease. They are in keeping with studies on the presence of certain tissue types (HLA B27, and HLA B8) in those with asbestosis and of non-specific auto-antibodies (anti-nuclear factor, rheumatoid factor) in asbestosis, silicosis and the idiopathic pulmonary fibrosis. The relation between genetic factors and asbestos-induced cancer is suggested by the variable susceptibility of different kinds of animals to carcinogenesis in response to asbestos and by the increased inductibility of the enzyme system Aryl-hydrocarbon-hydroxylase in subjects exposed to this air-born contaminant who develop pleural tumours and/or bronchitis. There are only two other publications of bronchial carcinoma in twins in the literature.

Mosaicism T(9;22) / t(1;9;22) was found in the bone marrow of a patient who had chronic myelocytic leukemia for 6 years. This finding suggest that complex translocation could be sometimes secondary to the usual t(9;22) translocation.

Cytogenetics studies were performed on the bone marrow aspirate in three cases of acute promyelocytic leukemia. In all of them the specific chromosome abnormality translocation t(15;17) was found. We obtained the chromosome preparations after a 48 h-culture. The exhibition of the t(15; 17) seems to be dependent on the methodology which is used.

In a general review of the different varieties of the intestinal polyposes, emphasis is laid upon the main three types of the so-called "genetic polyposes" (juvenile polyposis, Peutz-Jeghers syndrome, and adenomatous polyposis) because of their peculiar interest concerning the pathological diagnosis, prognosis and genetic background. A correct histological diagnosis is of the utmost importance before an appropriated treatment can be initiated.

Gardner's syndrome, an hereditary affection of the different blastoderm layers, is rarely recognised, even though it is seen in 8-16% of cases of colorectal polyposis. The authors present 7 cases of Gardner's syndrome within 3 families: 4 female and 3 male. Six of the patients belonged to 2 families, of which several members suffered from familial polyposis; the seventh case was an isolated case of Gardner's syndrome, without a family history of polyposis. Because of the high risk of malignancy in the presence of polyps, the treatment of Gardner's syndrome is identical to that of familial polyposis, 4 patients underwent total colectomy, 2 a simple polypectomy and 1 refused all treatment or monitoring. From these patients, one of the polyps excised at the level of the rectum was found to be undergoing malignant transformation. The extra-colic manifestations of this condition precede the polyposis within the gut; they attract attention and thus permit an early diagnosis.

The authors report an observation of retinoblastoma associated with partial monosomy 13q [46, XY, t (2;10) (q21;q24), inv(9), del(13)(q13q213)] and discuss the origin of this exceptional childhood tumor by gene mutation of chromosome rearrangement.