Abstract
An idic(Xp-) in which the two X chromosomes are attached short arm to short arm, and which thus has two b regions (the Q-dark segment next to the centromere on Xp) between the inactivation centers, assumed to be situated on the Q-dark region next to the centromere on Xq, showed 63.8% bipartite Barr bodies as compared with 22.2% formed by idic(Xq-). In addition, the mean distance of the two parts of the Barr bodies in the fibroblasts of a patient with idic(Xp-) is significantly greater than in the cases with one or no b region. Contrary to the other patients with abnormal X chromosomes, the buccal cells of a woman idic(Xp-) showed a number of bipartite Barr bodies. — To explain these observations we have put forward the hypothesis that the b region on the Xp always remains active and thus, when the rest of the chromosome forms a Barr body, this segment is extended, allowing the two parts of the X chromatin to get farther apart and at the same time increasing the percentage of bipartite bodies.
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Allderdice, P.W., Miller, O.J., Klinger, H.P., Pallister, P.D., Opitz, J.M.: Demonstration of a spreading effect in an X-autosome translocation by combined autoradiographic and quinacrinefluorescence studies. (Abstr.) Exc. Med. Int. Congr. Ser. 233, 14–15 (1971)
Buckton, K.E., Jacobs, P.A., Rae, L.A., Newton, M.S., Sanger, R.: An inherited X-autosome translocation in man. Ann. hum. Genet. (Lond.) 35, 171–178 (1971)
Chapelle, A. de la, Schröder, J.: Reappraisal of a 46,X, i(Xp) karyotype as 46,Xdel(Xq). Hereditas (Lund) 80, 137–140 (1975)
Chapelle, A. de la, Stenstrand, K.: Dicentric human X chromosomes. Hereditas (Lund) 76, 259–268 (1974)
Daly, R.F., Patau, K., Therman, E., Sarto, G.E.: Structure and Barr body formation of an Xp+ chromosome with two inactivation centers. Amer. J. hum. Genet. 29 (in press 1977)
Darlington, C.D., La Cour, F.L.: The handling of chromosomes. Darien, Conn.: Hafner Publ. Co. 1970
DeMars, R., Nance, W.E.: Electrophoretic variants of glucose-6-phosphate dehydrogenase and the single-active-X in cultivated human cells. Wistar Inst. Symp. Monogr. 1, 35–48 (1964)
Distèche, C., Hagemeijer, A., Frederic, J., Progneaux, D.: An abnormal large human chromosome identified as an end-to-end fusion of two X's by combined results of the new banding techniques and microdensitometry. Clin. Genet. 3, 388–395 (1972)
Gouw, W.L., Coenegracht, J.M., Stalder, G.: A very large metacentric chromosome in a woman with symptoms of Turner's syndrome. Cytogenetics 3, 427–440 (1964)
Lyon, M.F.: Mechanisms and evolutionary origins of variable X-chromosome activity in mammals. Proc. roy. Soc. Lond. B 187, 243–268 (1974)
McKusick, V.A., Chase, G.A.: Human genetics. Ann. Rev. Genet. 7, 435–473 (1973)
Miller, R.: Simultaneous statistical inference. New York: MacGraw Hill 1966
Sarto, G.E., Therman, E., Patau, K.: Increased Q-fluorescence of an inactive Xq- chromosome in man. Clin. Genet. 6, 1–5 (1974)
Takagi, N., Oshimura, M.: Fluorescence and Giemsa banding studies of the allocyclic X chromosome in embryonic and adult mouse cells. Exp. Cell Res. 78, 127–135 (1973)
Therman, E., Patau, K.: Abnormal X chromosomes in man: origin, behavior and effects. Humangenetik 25, 1–16 (1974)
Therman, E., Sarto, G.E., Patau, K.: Center for Barr body condensation on the proximal part of the human Xq: a hypothesis. Chromosoma (Berl.) 44, 361–366 (1974a)
Therman, E., Sarto, G.E., Patau, K.: Apparently isodicentric but functionally monocentric X chromosome in man. Amer. J. hum. Genet. 26, 83–92 (1974b)
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Therman, E., Sarto, G.E., Distèche, C. et al. A possible active segment on the inactive human X chromosome. Chromosoma 59, 137–145 (1976). https://doi.org/10.1007/BF00328482
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DOI: https://doi.org/10.1007/BF00328482