Table 1.

Spectrum of Lethality Starting by E12.5

Stage	Total	WT Alive	WT Dead	TAZKD Alive	TAZKD Dead	P-value (Fisher's)
E12.5	14	7	1	3	3	0.245
E13.5	67	31	2	29	5	0.428
E14.5	28	18	1	3	6	0.001
Newborn	60	35	0	13	12	<0.0001

TAZKD indicates tafazzin knockdown (induced); WT, wildtype.

Mice were harvested at the stages shown in the Table; newborn mice were harvested within hours of birth. Fisher's exact test (two-tailed) was performed on 2×2 contingency tables of WT versus TAZKD mice, alive versus dead, and shows loss of expected Mendelian ratios of living TAZKD mice by E14.5. Additional data from longitudinal echocardiographic imaging of three litters further attested to prenatal and perinatal lethality: a total of 24 embryos (18 alive, six dead [nonresorbed]) were demonstrable at E12.5, but only 10 were born; eight lived (all WT) while two died early on the day of birth (both TAZKD).