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. 1991 Nov;49(5):1034–1040.

A molecular study of X isochromosomes: parental origin, centromeric structure, and mechanisms of formation.

I Lorda-Sanchez 1, F Binkert 1, M Maechler 1, A Schinzel 1
PMCID: PMC1683244  PMID: 1681727

Abstract

Fourteen individuals with an i(Xq) or idic(Xq) were studied using RFLP analysis in order to determine both parental origin and extent of heterozygosity of the isochromosome and to search for the presence of short-arm material. In five cases the isochromosome was paternally derived, while nine patients had a maternal i(Xq). The analysis of heterozygosity of the nine maternally derived isochromosomes by using Xq markers showed heterozygosity in two cases, suggesting an origin from two homologous X chromosomes. Homozygosity was found at all informative loci in seven cases, which therefore are probably the product of either centromere misdivision or sister-chromatid exchange. Presence of Xp markers was seen both in the three i(Xq) chromosomes which appeared dicentric by cytogenetic analysis and in three additional cytogenetically monocentric cases. Mean parental ages were greater for the maternally derived cases as compared with the paternally derived cases.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Antonarakis S. E., Adelsberger P. A., Petersen M. B., Binkert F., Schinzel A. A. Analysis of DNA polymorphisms suggests that most de novo dup(21q) chromosomes in patients with Down syndrome are isochromosomes and not translocations. Am J Hum Genet. 1990 Dec;47(6):968–972. [PMC free article] [PubMed] [Google Scholar]
  2. Callen D. F., Mulley J. C., Baker E. G., Sutherland G. R. Determining the origin of human X isochromosomes by use of DNA sequence polymorphisms and detection of an apparent i(Xq) with Xp sequences. Hum Genet. 1987 Nov;77(3):236–240. doi: 10.1007/BF00284476. [DOI] [PubMed] [Google Scholar]
  3. Carothers A. D., De Mey R., Daker M., Boyd E., Connor M., Ellis P. M., Stevenson D. An aetiological study of isochromosome-X Turner's syndrome. Clin Genet. 1989 Jul;36(1):53–58. doi: 10.1111/j.1399-0004.1989.tb03366.x. [DOI] [PubMed] [Google Scholar]
  4. Connor J. M., Loughlin S. A. Molecular genetics of Turner's syndrome. Acta Paediatr Scand Suppl. 1989;356:77–81. doi: 10.1111/j.1651-2227.1989.tb11251.x. [DOI] [PubMed] [Google Scholar]
  5. De la Chapelle A., Wennström J., Hortling H., Ockey C. H. Isochromosome-X in man. I. Hereditas. 1966;54(3):260–276. doi: 10.1111/j.1601-5223.1966.tb02021.x. [DOI] [PubMed] [Google Scholar]
  6. Deng H. X., Xia J. H., Ishikawa M., Niikawa N. Parental origin and mechanism of formation of X chromosome structural abnormalities: four cases determined with RFLPs. Jinrui Idengaku Zasshi. 1990 Sep;35(3):245–251. doi: 10.1007/BF01876853. [DOI] [PubMed] [Google Scholar]
  7. Fraser N. J., Boyd Y., Craig I. Isolation and characterization of a human variable copy number tandem repeat at Xcen-p11.22. Genomics. 1989 Jul;5(1):144–148. doi: 10.1016/0888-7543(89)90099-2. [DOI] [PubMed] [Google Scholar]
  8. Harbison M., Hassold T., Kobryn C., Jacobs P. A. Molecular studies of the parental origin and nature of human X isochromosomes. Cytogenet Cell Genet. 1988;47(4):217–222. doi: 10.1159/000132553. [DOI] [PubMed] [Google Scholar]
  9. Heilig R., Oberlé I., Arveiler B., Hanauer A., Vidaud M., Mandel J. L. Improved DNA markers for efficient analysis of fragile X families. Am J Med Genet. 1988 May-Jun;30(1-2):543–550. doi: 10.1002/ajmg.1320300156. [DOI] [PubMed] [Google Scholar]
  10. Hsu L. Y., Paciuc S., David K., Cristian S., Moloshok R., Hirschhorn K. Number of C-bands of human isochromosome Xqi and relation to 45,X mosaicism. J Med Genet. 1978 Jun;15(3):222–226. doi: 10.1136/jmg.15.3.222. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Jacobs P. A., Betts P. R., Cockwell A. E., Crolla J. A., Mackenzie M. J., Robinson D. O., Youings S. A. A cytogenetic and molecular reappraisal of a series of patients with Turner's syndrome. Ann Hum Genet. 1990 Jul;54(Pt 3):209–223. doi: 10.1111/j.1469-1809.1990.tb00379.x. [DOI] [PubMed] [Google Scholar]
  12. Jeffreys A. J., Wilson V., Thein S. L. Hypervariable 'minisatellite' regions in human DNA. Nature. 1985 Mar 7;314(6006):67–73. doi: 10.1038/314067a0. [DOI] [PubMed] [Google Scholar]
  13. Mandel J. L., Willard H. F., Nussbaum R. L., Romeo G., Puck J. M., Davies K. E. Report of the committee on the genetic constitution of the X chromosome. Cytogenet Cell Genet. 1989;51(1-4):384–437. doi: 10.1159/000132801. [DOI] [PubMed] [Google Scholar]
  14. Otto P. A., Otto P. G. Paternal or maternal origin of human i(Xq) isochromosomes. Hum Genet. 1981;59(4):308–309. doi: 10.1007/BF00295462. [DOI] [PubMed] [Google Scholar]
  15. Sanger R., Tippett P., Gavin J. Xg groups and sex abnormalities in people of northern European ancestry. J Med Genet. 1971 Dec;8(4):417–426. doi: 10.1136/jmg.8.4.417. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Schmid W., Naef E., Mürset G., Prader A. Cytogenetic findings in 89 cases of Turner's syndrome with abnormal karyotypes. Humangenetik. 1974;24(2):93–104. doi: 10.1007/BF00283766. [DOI] [PubMed] [Google Scholar]
  17. Shaffer L. G., Jackson-Cook C. K., Meyer J. M., Brown J. A., Spence J. E. A molecular genetic approach to the identification of isochromosomes of chromosome 21. Hum Genet. 1991 Feb;86(4):375–382. doi: 10.1007/BF00201838. [DOI] [PubMed] [Google Scholar]
  18. Sharp C. B., Bedford H. M., Willard H. F. Pericentromeric structure of human X "isochromosomes": evidence for molecular heterogeneity. Hum Genet. 1990 Aug;85(3):330–336. doi: 10.1007/BF00206757. [DOI] [PubMed] [Google Scholar]
  19. Villamar M., Fernandez E., Ayuso C., Ramos C., Benitez J. Study of the parental origin of sexual aneuploidy in ten families using RFLPs. Ann Genet. 1990;33(1):29–31. [PubMed] [Google Scholar]

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