Genetics, Vol. 161, 1219-1224, July 2002, Copyright © 2002

Molecular Analysis of Nondisjunction in Mice Heterozygous for a Robertsonian Translocation

Lara A. Underkofflera, Laura E. Mitchella,b, A. Russell Localiob, Shannon M. Marchegiania, Justin Morabitoa, Joelle N. Collinsa, and Rebecca J. Oakeya
a Division of Human Genetics, The Children's Hospital of Philadelphia,
b Department of Biostatistics and Epidemiology and Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104

Corresponding author: Rebecca J. Oakey, GKT School of Medicine, 8th Floor, Guy's Tower, London Bridge, London SE1 9RT, UK., rebecca.oakey{at}kcl.ac.uk (E-mail)

Communicating editor: C. KOZAK

A Robertsonian translocation results in a metacentric chromosome produced by the fusion of two acrocentric chromosomes. Rb heterozygous mice frequently generate aneuploid gametes and embryos, providing a good model for studying meiotic nondisjunction. We intercrossed mice heterozygous for a (7.18) Robertsonian translocation and performed molecular genotyping of 1812 embryos from 364 litters with known parental origin, strain, and age. Nondisjunction events were scored and factors influencing the frequency of nondisjunction involving chromosomes 7 and 18 were examined. We concluded the following:

  1. The frequency of nondisjunction among 1784 embryos (3568 meioses) was 15.9%.

  2. Nondisjunction events were distributed nonrandomly among progeny. This was inferred from the distribution of the frequency of trisomics and uniparental disomics (UPDs) among all litters.

  3. There was no evidence to show an effect of maternal or paternal age on the frequency of nondisjunction.

  4. Strain background did not play an appreciable role in nondisjunction frequency.

  5. The frequency of nondisjunction for chromosome 18 was significantly higher than that for chromosome 7 in males.

  6. The frequency of nondisjunction for chromosome 7 was significantly higher in females than in males.

These results show that molecular genotyping provides a valuable tool for understanding factors influencing meiotic nondisjunction in mammals.




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L. A. Underkoffler, L. E. Mitchell, Z. S. Abdulali, J. N. Collins, and R. J. Oakey
Transmission Ratio Distortion in Offspring of Mouse Heterozygous Carriers of a (7.18) Robertsonian Translocation
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