Abstract
The analysis of transgenic and knockout mice always involves the establishment of matings with individuals carrying different loci, segregating independently, whose presence is expected among the progeny, according to a Mendelian distribution. The appearance of distorted inheritance ratios suggests the existence of unexpected lethal or sub-lethal phenotypes associated with some genotypes. These situations are common in a number of cases, including: testing transgenic founder mice for germ-line transmission of their transgenes; setting up heterozygous crosses to obtain homozygous individuals, both for transgenic and knockout mice; establishing matings between floxed mouse lines and suitable cre transgenic mouse lines, etc. The Pearson’s χ2 test can be used to assess the significance of the observed frequencies of genotypes/phenotypes in relation to the expected values, in order to determine whether the observed cases fit the expected distribution. Here, I describe a simple Excel workbook to compare the observed and expected distributions of genotypes/phenotypes in transgenic and knockout mouse crosses involving up to three unlinked loci by means of a χ2 test. The file is freely available for download from my laboratory’s web page at: http://www.cnb.csic.es/~montoliu/Mendel.xls.
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Acknowledgments
The author thanks Thomas J. Fielder for critically reviewing this manuscript, and Laura Barrios and Carlos O. Sanchez-Sorzano for professional advice on statistics. This work was supported by MEC funds BIO2003-08196 and BFU2006-12185 and MICINN project BIO2009-1297 to LM.
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Montoliu, L. Mendel: a simple excel workbook to compare the observed and expected distributions of genotypes/phenotypes in transgenic and knockout mouse crosses involving up to three unlinked loci by means of a χ2 test. Transgenic Res 21, 677–681 (2012). https://doi.org/10.1007/s11248-011-9544-4
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DOI: https://doi.org/10.1007/s11248-011-9544-4