Berta Santesson

Association Between Congenital Heart Malformation and Chromosomal Variations1

A family is described in which mother rind son both displayed auricular septal defects of the secundum type while father and daughter had no cardiovascular disorders. The karyotypes of these individuals were analysed by the cell culture method using biopsies from bone marrow and skin. The majority of the cells from the mother had 47 chromosomes and she was apparently trisomic [19‐201. A similar additional chromosome of group [19‐201 wasfound in the cells derived from the son.

Three non‐mongoloid patients of similar phenotype with an extra G‐like chromosome

Three mentally retarded non‐mongolid children with very similar clinical signs and an extra G‐like chromosome are presented. In one of these patients, Case I, an attempt to trace the origin of the extra chromosome has been made by QM fluorescence analysis and autoradiography. Visually the QM pattern of the extra chromosome differs from that of chromosomes 21 and 22 by showing a diffuse fluorescence of intermediate intensity in the long arm, not unlike that found in the proximal part of the long arm of chromosome no. 13. However, whether these are sufficiently similar to indicate homologous regions cannot be decided. The autoradiographic pattern is not decisive as to the origin of the extra chromosome; it shows early labelling, as do no. 22 and the short arm and proximal part of the long arm of no. 13.

Different baseline sister chromatid exchange levels in density fractionated human lymphocytes

SummaryDifferent activation states of B and T lymphocytes, as manifested by differences in cell density, were obtained by Percoll density centrifugation of unstimulated human lymphocytes. Four different density fractions were defined: B cells with low (1.043 g/ml) and high (1.056) density, and T cells with low (1.067) and high (1.077) density, respectively. Sister chromatid exchange (SCE) conditions and proliferation rates were determined. Total B cells, stimulated by the bacterial mitogen Branhamella, had 4.6 SCE per cell, the lowest mean baseline SCE level recorded among lymphocytes. The growth rate was intermediate between that of low and high density T cells. The two T cell fractions stimulated by phytohemagglutinin (PHA) had different baseline SCE frequencies and different growth characteristics: the low density cells had 5.7 SCEs per cell and a short cell cycle, whereas high density cells had 12.5 SCEs per cell and a longer cell cycle. The differences in baseline SCE frequency and growth characteristics between the two T cell fractions seem to be correlated with the differences in the activation state as reflected by the cell density. Both high and low density T cell are G0 populations which supposedly differ with respect to previous history in vivo such as age and contact with antigens. The reason why these cells react differently to bromodeoxyuridine (BrdU) is unknown, but differences in intracellular DNA precursor pools and enzyme activities might play a role.

Mosaic trisomy of an autosome in the 6-12 group in a patient with multiple congenital anomalies.

Three autosomal trisomies are known to be associated with well defined clinical syndromes. They are mongolism with 21 trisomy [lo], 13-15 trisomy [12] and 17-18 trisomy [3]. An extra autosome among the chromosomes of the 6-12 group in all cells of the body seems in most instances to be lethal and has hitherto, except in spontaneous abortions [2, 221, only been reported in a mentally retarded girl with multiple anomalies [7]. However, chromosome studies were made only on peripheral blood cells. Normal/6-12 trisomy mosaicism, on the other hand, i.e. the presence of a certain proportion of normal cells together with cells with 47 chromosomes, seems to have less drastic effects. To our knowledge 6 such cases of possible mosaic trisomy for a 6-12 autosome have been reported [a, 6, 13, 17, 19, 20, 211. Furthermore, a premature non-viable infant has been reported [HI, who possessed two abnormal stemlines, one with an additional small chromosome and another with an additional autosome in group 6-12. We have observed a further case of mosaic trisomy for one of the autosomes in the 6-12 group 44 67287 1 Acta Pzdiat Scand 56 in a mentally retarded boy with multiple anomalies, including agenesis of the corpus callosum.

Chromosome and chromatid-type aberrations induced by cobalt60 irradiation and tritiated uridine in human leukocyte cultures

Human short term leukocyte cultures have been exposed to Co60 and H3-uridine irradiation. At the time of their first mitotic event the cells are collected. In the cultures treated with H3-uridine mainly breaks of chromatid type are found, whereas the Co60 irradiated cells have only breaks of chromosome type as long as the irradiation takes place before the onset of DNA synthesis. It is inferred that H3-uridine causes damage to localized single stranded DNA loops separated during transcription in RNA synthesis and inaccessible to repairing. The results are interpreted as an indication that the chromosome (chromatid) continuity is dependent on one DNA double helix strand and that the subunits of the chromosome, as revealed by radiation, is in fact single-stranded DNA.

Chromosomal Abnormality in a Mongolism-Like Syndrome1

The cytogenetical and clinical observations of a 4 year old girl with a mongolism‐like syndrome are reported. The patient showed a moderate mental and physical retardation. Some signs and symptoms considered characteristic of mongolism were present. Others, such as the dermal patterns of hands and feet, rather contradict this diagnosis. In addition the patient had a bilateral dislocation of the hips and unspecific signs of retinal degeneration. There were no signs of abnormal sexual development.

Male pseudohermaphroditism with 45X/46XYq- mosaicism in a pair of monozygotic twins

Male pseudohermaphroditism with 45, X/46, XYq‐mosaicism in a pair of monozygotic twins is reported. The twins showed ambiguous external genitalia with labial fusion, hypertrophy of the clitoris and a vagina which ended in the distal part of the urethra. A uterus and two Fallopian tubes were also present. One of the twins had two gonads, both with testicular structure. In the other twin a gonad could be shown only on the right side; it had testicular structure. Both twins were reared as girls and the external genitalia were reconstructed in a female direction. They both showed 45, X/46, XYq‐mosaicism with similar proportion of XYq‐cells in cultures from blood, skin and testes. The significance of the mosaicism in the aetiology of the intersex condition is discussed.

DNA synthesis of human XYY cells. Autoradiography and fluorescence pattern.

The autoradiographic YY labelling pattern of the DNA replication in 47, XYY cells of two patients has been studied. Both Y chromosomes began DNA replication simultaneously but later than the rest of the chromosomes. During later stages the YY labelling pattern in both patients was correlated to the position of the cells in S, as indicated by the cell grain count: in cells with more than approximately 500 grains the synchronous labelling of the Y chromosomes was the rule; whereas during later stages in cells with approximately 100–400 grains, synchronous as well as asynchronous labelling in the same patient was found. In cells with less than about 100 grains, both Y chromosomes usually had completed replication. No obvious difference between the labelling pattern of the two Y chromosomes was found when cells from the 2 patients were compared at the same stage of S. Our results demonstrate the importance of analysing cells of comparable developmental stages of S when comparing DNA labelling patterns of different XYY individuals in search of a possible correlation between labelling pattern and phenotypic expression of the syndrome.