Expression of tyrosine kinases encoding protooncogenes in differentiating human leukemia-cells.

We investigated the expression of the tyrosine kinase encoding proto-oncogenes c-src and fyn during in vitro differentiation of the human promyelocytic leukemia cell line HL-60 and an HL-60 derived cell line (HL-GOT) with an altered T-cell receptor gene. In HL-60 cells, the fyn and c-src encoded tyrosine kinases are activated in a differentiation-dependent manner, whereas in HL-60T cells high levels of pp59(fyn) and pp60(c-src) specific kinase activities are already present in the untreated cells. From the data obtained we conclude that untreated HL-60T cells represent a more differentiated type of cells compared to the untreated promyelocytic HL-60 cells.

Chromosome 18 variant with increased centromeric tandemly repeated DNA in a family.

At amniocentesis of a woman in her forties, a familial abnormal chromosome 18 is found. The very elongated short arm is shown to consist partially of centromeric heterochromatin of 18 by specific DNA probe. The newborn develops normally.

[Constitutional stereotyped gap in human chromosomes (author's transl)]. / Lacune stéréotypée constitutionnelle des chromosomes humains.

The stereotyped break with gap of a chromosomal variant is rarely observed. This anomaly is transmitted according to autosomal dominant rule. The distal part of the broken chromosome may either be still bound to the sister chromatid through mitotic non-disjunction, forming a triradial figure, or take a moniliform and pulverized appearance, evoking premature chromosome condensation.

Partial deletions and trisomies of chromosome 13; mapping of bands associated with particular malformations.

New techniques of human karyotyping have allowed us to define accurately the banding pattern of six new cases with partial duplication of deficiency of chromosome 13. It now seems possible to draw a rough map of chromosome 13, correlating observed malformations and phenotypic features with specific chromosome regions. Partial monosomy shows clinical features which are the antithesis of the corresponding trisomic phenotype (Lejeune 1966).

Exchange of terminal portions of X- and Y-chromosomal short arms in human XY females.

Human Y(+) XX maleness has been shown to result from an abnormal terminal Xp-Yp interchange that can occur during paternal meiosis. To test whether human XY females are produced by the same mechanism, we followed the inheritance of paternal pseudoautosomal loci and Xp22.3-specific loci in two XY female patients. Y-specific sequences and the whole pseudoautosomal region of the Y chromosome of their fathers were absent in these patients. However, the entire pseudoautosomal region and the X-specific part of Xp22.3 distal to the STS locus had been inherited from the X chromosome of the respective father. This Xp transfer to Yp was established by in situ hybridization experiments showing an Xp22.3-specific locus on Yp in both cases. Such results demonstrate that an abnormal and terminal X-Y interchange generated the rearranged Y chromosome of these two XY females; they appear to be the true countertype of Y(+) XX males. In these patients, who also display some Turner stigmata, the Y gene(s) involved in this phenotype is (are) localized to interval 1 or 2. If the loss of such gene(s) affects fetal viability, their proximity to TDF would account for the underrepresentation of interchange 46,XY females compared with Y(+) XX males.

Mapping of probe p49f to the proximal part of the human Y chromosome long arm.

Probe 49f, subcloned from the Y chromosome locus DYS1, had previously been located to Yq.11 by deletion mapping. Using in situ hybridization techniques we mapped the probe more precisely to subband Yq11.2.

Interstitial deletion and ring chromosome derived from 19q. Proximal 19q trisomy phenotype.

A small supernumerary ring chromosome has been found in a boy with overweight, dysmorphic facies and mental retardation. His mother had an interstitial deletion of the long arm of chromosome 19 and the same ring chromosome. By means of fluorescence in situ hybridization the ring chromosome was shown to be derived from the deleted chromosome, after the occurrence of two breaks: one in the centromere region, the other in the q-arm of chromosome 19.

Application of fluorescence in situ hybridization to the identification of different marker chromosomes.

Chromosome studies performed on lymphocyte culture of a baby with specific dysmorphism and congenital anomalies suggestive of trisomy 21 revealed a mosaicism: 46,XY,rea(21q21q) [25]/47,XY,rea(21q21q),+mar1[25]. The karyotype of the mother is normal, but the father's karyotype presents an supernumerary chromosome greater and different from the marker of his son: 47,XY,+mar2 (100%). The identification of the two marker chromosomes by standard cytogenetic techniques followed by molecular techniques is essential for the identification of the origin of these two chromosomes. The unusual presence of two different markers one in the father and one in the son, as well as the clinical features of the child, are presented. The possible role of the paternal marker, in the de novo chromosomal rearrangement in his child will be discussed.

[7 cases of trisomy 2q34 leads to 2qter resulting from a familial t(2;8)(q34;23)]. / Sept cas de trisomie 2q34 leads to 2qter par transmission familiale d'une translocation t(2;8)(q34;p23).

Seven patients from two different families are trisomic 2q34 leads to 2qter due to segregation of a familial t(2;8)(q34;p23). The clinical features are characteristic: microcephaly, a narrow forehead with bossing and temporal retraction, hypertelorism, palpebral fissures slanted downwards, large irides, and a very concave margin of the lower eyelid. Mental retardation is severe with a mean IQ of 50.

Meiotic analysis of two human reciprocal X-autosome translocations.

Two cases of human reciprocal X-autosome translocation, t(X;12) and t(X;2), are described in sterile males, along with meiotic findings. Each carrier had inherited the translocation from his mother. Both showed azoospermia and germ-cell maturation arrest at the primary spermatocyte level, with most cells being arrested at the pachytene stage. A few metaphase I (MI) divisions were found, with occasional metaphase II cells being seen in the t(X;2) carrier. MI air-dried preparations gave clear evidence of chain quadrivalent formation. In the t(X;2) heterozygote, the pairing characteristics of the quadrivalent at pachytene were also analyzed in electron microscopic spreads. Disturbance of pairing around the breakpoints characterized most quadrivalents, and there was evidence in about 20% of the cells that nonhomologous pairing had taken place between the translocated chromosomes and the normal chromosome 2. Comparisons are made with similar nonhomologous pairing configurations seen at pachytene in quadrivalents of male reciprocal X-autosome translocations of the mouse.

Infertility in human males with autosomal translocations: meiotic study of a 14;22 Robertsonian translocation.

Pachytene analysis was undertaken in a male patient heterozygous for a 14q22q Robertsonian translocation. The relatively low rate of XY autosome association led us to examine the relationships existing between the chromosomes involved in the translocation, the rate of XY-autosome association and the degree of spermatogenic failure. Cytogenetic investigations in infertile men and the results of the meiotic studies suggest a direct correlation between the frequency of XY-autosome association at pachytene and the degree of spermatogenic failure. Whether associations arise as a consequence or cause of germ cell failure is still not certain.

Molecular definition of de novo and genetically transmitted WAGR-associated rearrangements of 11p13.

We describe a family in whom the phenotypically normal father carries a balanced insertional translocation, ins(14;11)(q23;p12p14). This individual fathered three mentally retarded children, two with a del(11)(p13) and one with a dup(11)(p13). Two other cases of a de novo del(11)(p13) are also described. All four del(11)(p13) cases presented with WAGR, a complex syndrome associated with a predisposition to Wilms' tumor (WT), aniridia (A), genitourinary abnormalities (G), and mental retardation (R). Using an approach combining karyotype analysis, determination of the gene copy number, and RFLP studies employing five 11p13 DNA markers, we were able to define the chromosomal rearrangement involved in each case. Analysis of these WAGR deletions provides further subdivision of band p13 on chromosome 11.