Biomedical subjects
Publications and source records attributed to M G Mattei.
The authors studied 17 cases of Robertsonian translocation. In all cases but one C banding showed that a dicentric translocation was involved. Silver staining demonstrated the presence of an NOR between the two centromeres in only one case.
Erythrocyte superoxide dismutase is a cuproprotein displaying increased activity in cases of trisomy 21. In this study, the three erythrocyte copper fractions were compared at constant serum copper levels in children with and without trisomy 21. The labile erythrocyte copper level was found to be identical in both groups of children. Total erythrocyte copper, especially the stable fraction, was increased in cases of trisomy 21. The approximately fifty per cent ob served increase correlates with the augmented superoxide dismutase activity related to the presence of an extra chromosome 21. Measurement of the stable erythrocyte copper fraction could constitute an indirect method for evaluating superoxide dismutase activity.
Dermal patterns in a group of Down's syndrome patients, a normal control population and a group of parents of Down's syndrome patients were studied in an attempt to identify an Index Score to be used in differentiating controls from parents of Down's syndrome children. Using only three patterns (simian crease, palmar hypothenar pattern and Cummins' Index), a parents' Index Score was established which correctly diagnosed 80.83% of controls and 79.17% of parents. The predictive value of this index and its interest in genetic counselling are discussed.
The distribution of break points in human chromosomes was analyzed in 15,754 metaphases from 1084 patients. A total of 1099 breaks were specifically localized to a chromosome band or region depicted in the PARIS CONFERENCE (1971) report. The sites of the breaks were very different from the expected random distribution and showed distinct clustering of breaks in some regions. These observations underline the heterogeneity of chromosomal material and furnish comparative data for the study of cytotoxic agents and constitutional chromosomal fragility.
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The authors report 47 cases of pericentric inversion. Eleven of them involve the chromosomes No. 2, 11 and 9. It appears that the risk of malformations and/or encephalopathy is obviously increased either by "position effect", aneusomie de recombinaison" or "interchromosomal effect". Prenatal diagnosis is therefore indicated. Thirty six cases involve the secondary constriction of chromosome No. 9. In such cases the risk is not enough increased to justify the prenatal diagnosis.
The authors report ten cases of structural anomalies involving the Y chromosome: five cases of a dicentric Y chromosome, one ring Y chromosome, one case of a Y isochromosome containing the long arms, one deletion of the long arms (Yq-), one case of an abnormally long Y chromosome (Yq+) and one Y-autosome translocation. Analysis of clinical and chromosomal correlations, especially with respect to sexual differentiation, led to discussing the role of the Y chromosome.
The authors discuss the clinical and cytogenetic problems raised in two new cases of X-chromosome translocations. The first case involves a child who presented marked malformations at age 3 months. Chromosome analysis revealed the presence of a translocation between a 22 and X chromosome resulting in partial X monosomy and partial trisomy 22: 46,X,der(X),t(X:22)(q112;q13)mat. The balanced translocation form was detected in the mother. Dynamic study after 5-Brdu treatment revealed inactivation of the translocated X chromosome in the proband, while in the mother the normal X chromosome was inactivated. In addition to magnesium dependent hypocalcemia resulting from a specific absorption anomaly, Case 2 presented discrete malformations and psychomotor retardation. Chromosome analysis revealed an apparently balanced translocation between a 9 and X chromosome: 46,X,t(9;X)(q12;p22). Treatment with 5-Brdu demonstrated that the translocated X chromosome was inactivated but that inactivation did not extend to the translocated part of chromosome 9. Finally, a pericentric inversion of a 9 chromosome was detected in the father, grandfather, and brother of the proband.
An unbalanced Y autosome translocation t(5;Y) and an apparently balanced translocation t(2;13) are identified with the Q and R banding in a 7-year-old boy with severe encephalopathy and a multiple malformation syndrome. At birth, the clinical diagnosis of 'cri du chat' syndrome based on the characteristic crying was not confirmed after karyotyping, using conventional staining techniques.
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A 12-year-old girl was examined for growth retardation and a few very discrete dysmorphologic stigmata of Turner's syndrome; the genitalia were infantile yet both ovaries possessed functioning follicles. R- and C-banding techniques and Brdu treatment demonstrated a 45,X formula in 95% of lymphocytes, with 5% presenting a 46,X,dic(X) formula. Cytogenetic and clinical problems raised by this observation are discussed in relation to data from the literature.
Dicentric Y chromosomes are rare in man. Four new cases of dicentric Y chromosomes are described. The cases of the literature so far reported are reviewed. Among the cases, a wide range of variation in phenotype, external genitalia, histology, and chromosomal findings was observed. The relationship of the clinical picture and structural abnormalities of the Y chromosomes is discussed.
The authors report a case of subacute myelocytic leukemia presenting some severe aspects. The cytogenetic findings show the Philadelphia chromosome ; t (9-22) and a second translocation between the chromosome 12, and the other chromosome 9 : t (9-12). They think that this second translocation represents a supplementary cytogenetic argument for the isolation of "Subacute myeloid Leukemia with Philadelphia chromosome" within chronic myeloid Leukemia.
The authors report an observation of partial trisomy 13p13 leads to qter and suggest a clinical map of chromosome 13. Increase of fetal hemoglobin seems to be controlled by region 1 of 13q. Bands q13 q14 and q21 seem to be responsible for inner organ malformations. Lastly, the distal segment q22 leads to qter is responsible for trigonocephaly and limb abnormalities.
Three very similar cases of sideroblastic idiopathic anemia were respectively observed for 105, 57 and 69 months. The cytogenetic blood study was normal. But the medullary genetic findings showed marker extra-chromosome, having the same aspect in each metaphase = 47 Mar +. It was respectively found in 13 mitoses/32, 2/45 and 1/30. The study of chromosome showed that it was not a normal cytogenetic C-chromosome at all, even it seemed to be a C - X type chromosome at first. The long arms had about the same size as the one of the C- type. But the short arms were really shorter. The study on R- bands showed a chromosomic marking unkown so far. The cytogenetic abnormalities described during the sideroblastic idiopathic anemias, the rare sideroblastic idiopathic anemias where were found a C- type chromosome really identified, then the well-defined myeloproliferative disorders having an extra- C chromosome, have been looked over again through the litterature. In each of our three studies we can think that these myelodysplasia are real mysloproliferative disorders because of the same marker extra-chromosome, but even after nine months we did'nt observe any chromosomal sign of blastic transformation.
There were 18 individuals found to have a constitutional chromosome fragility causing an increase in break frequency. For each chromosome the breakpoint is always the same, whether it involves chromosomes from the same person, the same family, or different families. The fragile points are bands 10q24, 12q13, 16q21, 17p12, and Xq27. Autosomal constitutional fragility does not seem to have a phenotypic correspondence. They were found mostly in parents of children with chromosomal abnormalities or in couples with a history of repeated spontaneous abortions which permits one to raise the possibility of an interchromosomal effect. The six constitutional chromosomal fragilities of the X chromosome had in common the association of mental deficiency, delayed speech, and large malformed ears. The break points in constitutional chromosomal fragility were compared to those of spontaneous breaks in vitro, to those induced by X-rays, and to those in Fanconi's anemia. The theoretical consequences of these structural abnormalities are discussed as well as what to do about them when they are found.
This study involving 109 normal subjects shows that the mean number of associations by cell seems to represent a biological constant which is not sex related and increases with age, especially after 33 years. From a qualitative point of view, the associations are not at random and their distribution varies from one individual to another. The tendency to associate is a characteristic of a given chromosome in a given individual.
Breakpoint distribution was studied from cultured lymphocytes on 7653 metaphases from 524 subjects whose karyotypes were normal. The mean break rate was 5% in both sexes. The frequency increased significantly after 40 years and varied during the year. The location of the breaks was very different from the expected random distribution. The break frequency for each chromosome was different according to the type of break (chromatid, simple chromosomal and chromosomal involving rearrangements). The location of the breaks was also studied according to type of band and with respect to the centromere. A comparison between spontaneous breaks, X-ray induced breaks, breaks in Fanconi's anemia had in congenital rearrangements, show very significant differences.