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Human Genetics

, Volume 89, Issue 1, pp 114–116 | Cite as

Genotype mosaicism in fragile X fetal tissues

  • Doris Wöhrle
  • Mark C. Hirst
  • Ingo Kennerknecht
  • Kay E. Davies
  • Peter Steinbach
Short Communications

Summary

The fragile X syndrome is one of the most common familial causes of mental retardation. It is associated with the expression of a fragile site at Xq27.3, although not all individuals carrying the mutation are fragile-X-positive. Recently, the mutation causing this disease has been identified as the amplification of, or insertion into, a CGG repeat sequence at the fragile site. The mutated chromosome can be recognised by the decrease in mobility of the EcoRI fragment that covers the mutated region. Analysis of lymphocytes of affected males often gives a number of different sized fragments indicating somatic heterogeneity. We have investigated this mosaicism in various tissues of an affected fetus in order to determine the extent of the variation between tissues, and to ascertain how to interpret the results in lymphocytes. Our results suggest that the heterogeneity occurs in all fetal tissues, but that the pattern of fragments observed varies between tissues. Methylation across the region also varies. These differences may be reflected in the cellular phenotypes and may influence the ultimate expression of the clinical phenotype.

Keywords

Internal Medicine Metabolic Disease Mental Retardation Repeat Sequence Clinical Phenotype 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Doris Wöhrle
    • 1
  • Mark C. Hirst
    • 2
  • Ingo Kennerknecht
    • 1
  • Kay E. Davies
    • 2
  • Peter Steinbach
    • 1
  1. 1.Abteilung Klinische Genetik der UniversitätUlmFederal Republic of Germany
  2. 2.Molecular Genetics GroupInstitute of Molecular Medicine, John Radcliffe HospitalOxfordUK

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