TABLE 2.
Frequency of NTDs as a function of embryonic Shmt1 genotype1
| Embryo Shmt1+/+ |
Embryo Shmt1+/− |
Embryo Shmt1−/− |
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| Diet and maternal genotype | NTDs, n (%) | Embryos, n | NTDs, n (%) | Embryos, n | NTDs, n (%) | Embryos, n |
| C | 0 (0) | 31 | 0 (0) | 62 | 0 (0) | 27 |
| Shmt1+/+ | 0 (0) | 31 | 0 (0) | 36 | — | — |
| Shmt1−/− | — | — | 0 (0) | 26 | 0 (0) | 27 |
| C+T | 0 (0) | 25 | 0 (0) | 63 | 0 (0) | 32 |
| Shmt1+/+ | 0 (0) | 25 | 0 (0) | 35 | — | — |
| Shmt1−/− | — | — | 0 (0) | 28 | 0 (0) | 32 |
| C+U | 1 (2.9) | 35 | 6 (10.3) | 58 | 1 (3.9) | 26 |
| Shmt1+/+ | 1 (2.9) | 35 | 4 (11.8) | 34 | — | — |
| Shmt1−/− | — | — | 2 (8.3) | 24 | 1 (3.9) | 26 |
| C+dU | 0 (0) | 16 | 0 (0) | 50 | 0 (0) | 27 |
| Shmt1+/+ | 0 (0) | 16 | 0 (0) | 23 | — | — |
| Shmt1−/− | — | — | 0 (0) | 27 | 0 (0) | 27 |
| FD | 0 (0) | 22 | 6 (12.2) | 49 | 2 (9.5) | 21 |
| Shmt1+/+ | 0 (0) | 22 | 1 (5.0) | 20 | — | — |
| Shmt1−/− | — | — | 5 (17.2) | 29 | 2 (9.5) | 21 |
| FD+T | 1 (4.6) | 22 | 2 (4.4) | 45 | 2 (14.3) | 14 |
| Shmt1+/+ | 1 (4.6) | 22 | 1 (3.7) | 27 | — | — |
| Shmt1−/− | — | — | 1 (5.6) | 18 | 2 (14.3) | 14 |
| FD+U | 2 (8.0) | 25 | 5 (8.9) | 56 | 6 (30.0) | 20 |
| Shmt1+/+ | 2 (8.0) | 25 | 2 (6.5) | 31 | — | — |
| Shmt1−/− | — | — | 3 (12.0) | 25 | 6 (30.0) | 20 |
| FD+dU | 0 (0) | 17 | 0 (0) | 50 | 0 (0) | 18 |
| Shmt1+/+ | 0 (0) | 17 | 0 (0) | 21 | — | — |
| Shmt1−/− | — | — | 0 (0) | 29 | 0 (0) | 18 |
Frequency of NTDs observed in litters isolated from crosses of Shmt1-deficient mice on a 129/SvEv background on gestational day 11.5. The effect of embryo genotype on NTD occurrence was not significant (P > 0.05). A set of a priori hypotheses between diets (C+T, C+U, and C+dU vs. C; FD vs. C; FD+T, FD+U, and FD+dU vs. FD) within each embryo genotype was tested by using exact tests. A Bonferroni correction was applied as a correction for multiple comparisons. C, control diet; C+dU, control diet supplemented with 2′-deoxyuridine; C+T, control diet supplemented with thymidine; C+U, control diet supplemented with uridine; FD, AIN-93G lacking folic acid; FD+dU, folate-deficient diet supplemented with 2′-deoxyuridine; FD+T, folate-deficient diet supplemented with thymidine; FD+U, folate-deficient diet supplemented with uridine; NTD, neural tube defect; —, embryonic genotype not observed from these dams.