J. Lejeune

Systematic analysis of 95 reciprocal translocations of autosomes.

SummaryThe statistical analysis of 95 cases of reciprocal translocations involving autosomes detected among about 10,000 patients studied with the R-banding technique gives the following information:1.An excess of break points exists for chromosome arms 4p, 9p, 10q, 21q, and 22q and a deficiency for 1p, 2p, and 6q. Furthermore, there are relatively more break points in the small arms than in the large arms, when the translocation is ascertained through an unbalanced translocation carrier. Except for chromosome 22, and ascertainment bias explain this non random distribution.2.An excess of telomeric break points exists in all cases of translocations ascertained through unbalanced carriers, and an excess of centromeric break point exists in the case of 3:1 and 1:3 segregations only. These excesses are also explained by an ascertainment bias.3.The break points are located usually at the junction of the bands (interfaces).4.The size of the chromosomal imbalance varies in the ascertainment classes. It is very large in cases ascertained through balanced carriers (at least one break point is far from the telomere), large in cases ascertained through abortion, and relatively moderate in cases ascertained through unbalanced translocation carriers (at least one break point is juxta telomeric).5.An excess of balanced reciprocal translocations exists in our sample of mentally retarded and malformed children (position effect?).6.An excess of balanced reciprocal translocations (not involving chromosome 21) exists among the trisomics 21 and their parents (interchromosomal effect?).7.A large excess of maternal transmission exists in cases of 3:1 segregation of reciprocal translocation. Deleterious effects of the reciprocal translocations are widely known, but their relation to the topologic changes of the chromatids needs further investigation. Thus, it seemed useful to analyze carefully the 95 reciprocal translocations observed among the 9183 patients studied since banding techniques became available in our laboratory.Our intention was to seek a correlation among the localization of break points, the chromosomes or segments there of involved in the rearrangements, and the types of segregation observed in the families ascertained.

Trisomie 21 et superoxyde dismutase-1 (IPO-A): Tentative de localisation sur la sous bande 21 q 22.1☆

Abstract The enzymatic activity of SOD-1 in erythrocytes has been studied in several cases of partial monosomies and full and partial trisomies 21. The following results are obtained: 1. The excess of SOD-1 activity in the case of the regular trisomy 21 is confirmed. 2. In monosomy 21 p ter→21 q 21, the enzymatic activity is normal. 3. In trisomy 21 p ter→21 q 21, the enzymatic activity is equally normal. 4. In trisomy 21 q 22, and more precisely in trisomy 21 q 22.1, the activity is increased. Consequently, the SOD-1 gene locus, previously assigned to chromosome 21, is very likely localised in sub-band 21 q 22.1. Finally, the phenotypic analysis indicates that the trisomy of this sub-band is responsible for a great part of the clinical features of trisomy for the whole chromosome 21. The possible role of the SOD-1 excess in the pathogeny of trisomy 21 is discussed.

Analyse des échanges de chromatides dans les cellules somatiques humaines

A new technique (BUdR treatment followed by acridine orange staining) allowing a differentiation of sister chromatids is described. A statistical analysis of 91 human karyotypes gives an estimate of the frequency of exchanges. The mean of sister chromatid exchanges is 27,3 and the minimum number is 11 per cell. — The frequency of these exchanges is proportional to the relative length of each chromosome, and the accumulation of several exchanges in some segments evokes the possibility of a “negative interference”. — The analysis of endomitoses treated with BUdR during at least two generations is not in disagreement with the model of semi-conservative replication of chromosomal DNA, but the modifications of the chromatids may result from a completely different process. — The frequency of endomitoses is increased by the treatment. These endomitoses allow a very precise analysis of the evolution of the sister chromatid exchanges, during two successive cellular generations.

CHROMOSOMAL AUTORADIOGRAPHY IN THE CRI DU CHAT SYNDROME.

The pattern of DNA synthesis in the chromosomes of Group 4–5 has been analysed in cells from individuals with the cri du chat syndrome. The abnormal chromosome, a No. 5, is one of t

Comparison of banding patterns of human chromosomes obtained with heating, fluorescence, and proteolytic digestion

Banding patterns of human chromosomes obtained with various new techniques-quinacrine mustard staining, staining after heating, and staining after proteolytic digestion —are compared. Depending on the

Pure partial trisomy of the short arm of chromosome 5

SummaryWe describe a male infant with multiple dysmorphic features who is trisomic for chromosome segment 5p13.32→5p14.2 as a result of recombination aneusomy. His father is a balanced carrier of an inverted insertion of this chromosome segment. The clinical features of this patient are compared with those of other patients with isolated partial 5p trisomy reported in the literature.

Translocation 8–22 sans changement de longueur et trisomie partielle 8q: Detection par denaturation ménagée

Abstract In two brothers, a supernumerary small acrocentrics indicated a trisomy for the distal part of the long arm of chromosome 8. By heat denaturation, a reciprocal translocation was found in the mother. In her 46, XX, t (8; 22) (q22; q 11) caryotype, the rearranged elements exhibit no change of length.

Contribution of magnetic resonance imaging to the knowledge of CNS malformations related to chromosomal aberrations

SummaryTwelve patients presenting with various clinicopathological syndromes related to chromosomal diseases have been evaluated using magnetic resonance imaging. They include patients with trisomy 21, trisomy 18, trisomy 13, 4p-syndrome, 5p-syndrome, and 7p-syndrome. In all these patients karyotype studies were performed demonstrating the chromosomal aberrations. All patients were examined using magnetic resonance imaging to evaluate the head and neck malformations which may be specifically associated with their chromosomal anomaly. We were particularly interested in brain abnormalities and the morphological findings correlated with some pathologic anatomical findings. A review of the literature on neuropathological data is reported and compared with the in vivo anatomical results obtained using this highly anatomical non-ionising and non-invasive investigative procedure. Particular interest is paid to trisomy 21 in which all recognizable stereotyped morphological skull and brain malformations are depicted with magnetic resonance and some other malformations demonstrated such as the excessive forward bending and ascension of the brainstem which correlated well with a simian cephalic organization.

12pter → 12p 12.2: Possible assignment of human triose phosphate isomerase

SummaryRed cell triose-phosphate isomerase (TPI) was determined, together with other enzymes, in three patients with chromosome 12 abnormalities.In patient No. 1 (trisomy of the segment 12pter → 12q12) and in patient No. 2 (trisomy of the segment 12pter → 12p12.1), the TPI activity was significantly increased. In patient No. 3 (deletion of the segment 12p11 → 12p12.2), the TPI activity was in the normal range. These results suggest that the human TPI locus is located on the chromosome 12 short arm, between 12pter and 12p12.2.

Analyse du caryotype de Pan paniscus . Comparaison avec les autres Pongidae et l'Homme

The analysis of the karyotype of pygmee Chimpanzee (Pan paniscus), and its comparison with the one of Pan troglodytes shows some differences on chromosomes 2q, 7, 13, and 22. The study of the chromosomal rearrangements differentiating the Chimpanzees and the others Anthropoids and Man allows us to propose a filiation of ancestral species.