Table 1.

Loss of Nfia⁻ homozygous and heterozygous mice from wild-type (WT)/Nfia⁻ x WT/Nfia⁻ crosses

Progeny	Number of progeny with genotype
	WT/WT	WT/Nfia−	Nfia−/Nfia−
Male	17	17	8
Female	18	23	5
Total	35	40	13*
(Expected)	(35)	(70)	(35)

Heterozygous WT/Nfia⁻ mice were bred and the number of progeny of each genotype was scored. These numbers exclude any lost mice for which DNA was not obtained (<5%). The expected values are calculated assuming that the WT/WT homozygotes all survive and should represent 25% of the progeny. The apparent loss of heterozygotes (40/70) is not seen in male WT/Nfia⁻ × female WT/WT crosses and may represent a maternal effect phenotype. 

^*Only 4 Nfia⁻/Nfia⁻ mice survived more than 6 weeks after birth (4/102 total pups from nine litters). Most Nfia⁻/Nfia⁻ pups die within 1 day of birth with a few surviving up to 2 weeks and <5% surviving 6 weeks.