Impaired postnatal development in C/EBPbeta-deficient mice.

Tail DNA genotyping of fetal and neonatal mice from C/EBPbeta heterozygous parents was performed to determine whether the decreased number of surviving C/EBPbeta mutants was caused by prenatal or postnatal death. Eighty-four 3-week-old mice born of heterozygous parents had significantly lower numbers of C/EBPbeta-deficient offspring than the expected Mendelian ratio (29.8%+/+, 65.5%+/-, 4.76%-/-, P<0.05). The genotypes of 72 fetal mice from intercrossed heterozygotes showed approximately the expected 1:2:1 Mendelian ratio (18.1% +/+, 52.8% +/-, 29.2% -/-, P>0.05). No difference in the proportions by sex could be detected in these perinates. This data indicates that C/EBPbeta-deficient mice have unknown lethal problems between the embryonic stage and weaning.