Postnatal survival is reduced in Nav2-/- mice. Female Nav2 heterozygotes were mated with Nav2+/- and Nav2-/- males, and litters were examined and genotyped at embryonic days (E) 10.5 and 17.5, and postnatal days (P) 0, 7, 14, and 28; with a total of 90, 188, 348, 94, 93, and 791 offspring examined at each time point, respectively. A reduction in expected number live animals (<1.0) appears in the homozygote mutant (HOM) group after P0. At weaning (P28), only 60% of the expected number of homozygous mice are alive. Wild-type (WT) values remain around the expected ratio of 1.0 (indicated by the dotted line) at all time points.