Partial trisomy for long arm of chromosome 16.
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Biomedical subjects
Publications and source records attributed to K E Buckton.
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The results of a chromosome survey of 3993 liveborn infants, the majority of which have been studied using G-banding, are reported. The frequency of all types of chromosome abnormalities detected was similar to that found in previous newborn surveys, which were carried out on different socio-economic structure, but the incidence of aneuploid chromosome abnormalities was comparable in the two localities.
The segregation of human phosphoglycolate phosphatase has been studied in 52 independent human-rodent hybrids and 69 subclones. The results suggest that human PGP is on chromosome 16. Family data suggest that PGP is not close to 16qh or alpha Hp. The most likely regional assignment for PGP would appear to be 16p13 or 16p12, but a site on 16q cannot be entirely excluded. New data on 16qh and alpha Hp suggest that the male recombination fraction between these loci is about 0.2.
G- and R-banded chromosome preparations from eight of twelve 46,XX males, with no evidence of mosaicism or a free Y chromosome, were distinguished in blind trials from preparations from normal 46,XX females by virtue of heteromorphism of the short arm of one X chromosome. Photographic measurements on X chromosomes and on chromosome pair 7 in cells from twelve 46,XX males, eight 46,XX females, and four 46,XY males revealed a significant increase in the size of the p arm of one X chromosome in the group of XX males, independently characterised as being heteromorphic for Xp. No such differences were observed between X chromosomes of normal males and females or between homologues of chromosome pair 7 in all groups. The heteromorphism in XX males is a consequence of an alteration in shape (banding profile) and length of the tip of the short arm of one X chromosome, and the difference in size of the two Xp arms in these 46,XXp+ males ranged from 0.4% to 22.9%. From various considerations, including the demonstration of a Y-specific DNA fragment in DNA digests from nuclei of one of three XX males tested, it is concluded that the Xp+ chromosome is a product of Xp-Yp exchange. These exchanges are assumed to originate at meiosis in the male parent and may involve an exchange of different amounts of material. The consequences of such unequal exchange are considered in terms of the inheritance of genes located on Yp and distal Xp. No obvious phenotypic difference was associated with the presence or absence of Xp+. Thus, some males diagnosed as 46,XX are mosaic for a cryptic Y-containing cell line, and there is now excellent evidence that maleness in others may be a consequence of an autosomal recessive gene. The present data imply that in around 70% of 46,XX males, maleness is a consequence of the inheritance of a paternal X-Y interchange product.
The incidence of chromosome aberrations in peripheral blood lymphocytes of 197 dockyard workers has been followed over a 10-yr period. These workers were exposed to mixed neutron-gamma radiation during the refuelling of nuclear reactors, but most exposures were below the internationally accepted maximum permissible level of 5 rem per yr. There was a significant increase in chromosome damage with increasing exposure; aberration frequency was a linear function of dose and was unfluenced by age and time of blood sampling after exposure.
The distribution of satellite DNA and nucleolar organiser activity have been studied in a female with a new dicentric translocation chromosome derived from the maternal chromosomes 13 and 14. More than half the satellite DNA (60.5%) was lost in the translocation, together with both the nucleolar organiser regions (NOR'S). However, at least one NOR (chromosome 21) which was inactive in the mother (by the AgI reaction) is active in the subject, and this may be an example of functional compensation. The somatic cells of the mother of the subject, which do not have the translocation, show a high frequency of acrocentric associations, but these do not include any obvious excess of associations involving chromosomes 13 and 14, indicating that the high frequency of association in somatic cells is not in itself a predisposition to Robertsonian translocation in germ line cells. The father's chromosomes 9 both have more satellite DNA in the secondary constriction than normal, but this is not reflected in any obviously larger size of the C-band in this region.
The segregation of the Q-band polymorphisms in 32 families have been studied. From 90 matings in these families, there were a total of 208 offspring. In one of these offspring it could be shown that there had been a change of a fluorescent polymorphism, resulting in the loss of fluorescent intensity in the satellite of a chromosome 21. The origin of such a 'mutation' and a consideration of mutation rates is discussed.
Some families with abnormalities of chromosome 9 have been combined with others from the literature to show that AK1 and ABO must lie near the end of that chromosome. Current evidence suggests that both lie in band 9q34. MNSs, GPT and Gc can be excluded from chromosome 9.
Chromosome analysis using G-banding was carried out on cells from 65 males and 102 females of all ages from a random sample of the population. The frequency of aneuploid cells showed a significant increase with age in both sexes, and in females the increase in hypodiploidy and hyperdiploidy was more marked than in males, and involved a high proportion of cells that had lost or gained an X chromosome, 45,X cells being much more common than 47,XXX cells. In females, the occurrence of a "fragment" of an X chromosome also correlated with increasing age, and this "fragment" appears to be an X chromosome that has simply divided prematurely at the centromere. The effects of time in culture and of repeating cultures of blood samples from the same individual on proportions of abnormal cells of various types were also investigated, and the results are discussed in the light of findings from several other "ageing surveys".
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We have failed to measure the recombination fraction between 9qh and the ABO:AK1 linkage group. Since the total male map distance along chromosome 9 is likely to be at least 120 cM, calculated from male chiasmata counts (Hultén, 1974) they may well not be within measurable distance of each other. ACONs does not lie between ABO and AK1, but there is so little information on this marker from family studies that it could lie almost anywhere else on chromosome 9 and might be within measurable distance of 9qh. The map of chromosome 9 based on studies on families with normal karyotypes is summarized in Fig. 1. We hope to improve this map in a subsequent paper based on observations on families with abnormal karyotypes.
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The aberrations seen in chromosomes of human peripheral-blood lymphocytes, X-irradiated in vitro, have been analysed in three types of preparations, treated to give G-banding; R-banding; and G-banding followed by R-banding on the same cells. The data from cells subjected to both banding techniques reveals that 30 per cent of the sites of chromosome breakage are situated at he interfaces between dark- and - light-stained bands. The results of all the analyses show that approximately 30 per cent of all breaks were located in either the telomere (19-5 per cent) or centromere (11-3 per cent) regions. Chromosomes rich in R-band material were not preferentially damaged, but chromosomes 12, 15, and particularly 17, were involved in aberrations more frequently than would be expected on the basis of their length. No breaks were found on the Y chromosome in the 114 male cells analysed, but the X did not appear to be spared from damage either in the male cells analysed, but the X did not appear to be spared from damage either in the male cell or the 136 female cells analysed. G and/or R-banding enables a much more accurate analysis of aberrations than can be obtained from the use of conventional staining techniques, and with these methods, it is shown that the numbers of induced asymmetrical and symmetrical exchanges are similar.
The segregation of human enzymes and chromosomes has been studied in more than 30 independent primary human-rodent somatic cell hybrids and a series of 64 subclones. The results strongly suggest that the locus determining AK1, 'red cell' adenylate kinase, is on chromosome 9 in man, and hence that the locus for the ABO blood groups and that for the Nail-patella syndrome may also be assigned to this chromosome. Evidence is presented indicating that another adenylate kinase, nucleoside triphosphate adenylate kinase, and also the soluble form of aconitase, are probably syntenic with AK1, and that the mitochondrial form of aconitase is probably not syntenic with these loci.
The incidence of the various classes of C-band and Q-band polymorphisms on ten pairs of chromosomes in the human complement have been investigated in three Scottish populations, two from the mainland (newborn and 14 year olds) and one, of individuals over 65 years, from an island in the Outer Hebrides. Although there is an overall similarity between the populations, there are some differences, especially with the island group. For all populations, over 90% of the C-band size variants fall within the medium class. Rather more variation is found in the Q-band intensity polymorphisms: the island population appears to have fewer Brilliant and Intense variants than do the other two groups, 2-9 per person as compared to 4-2 and 3-9 for the newborn and 14 year olds respectively; this may be an age difference rather than a population difference.
The inheritance of C-band and Q-band polymorphisms have been investigated in 32 families. C-band inversion and size polymorphisms appear to segregate in a Mendelian manner, with the possible exception of the very large variant of chromosome number 9 which may be selectively inherited. There is some evidence to suggest a preferential segregation of Brilliant Q-band polymorphisms but it may be that this is an artifact caused by insufficient data and scoring error.