IUHSCT similarly allows for robust donor engraftment in homozygous Fanca^–/– mice with WT competitive advantage over time.Fanca^–/–, Fanca^+/−, and WT fetuses were generated as previously described for Fancd2^–/– mice. At E13.5-14.5, fetuses were transplanted via intrahepatic injection with 1 × 10⁶ CD117⁺ selected HSCs. Pups were genotyped and followed (WT, n = 2; Fanca^+/−, n = 4; and Fanca^–/–, n = 2). Peripheral blood and BM donor chimerism was assessed by flow cytometry (% CD45.1) at various time points after IUHSCT. (A) Multilineage donor chimerism was examined in (A) granulocytes and (B) lymphocytes, including B cells, CD4 helper T cells, and CD8 cytotoxic T cells. (C) LT-HSC chimerism was also determined. Data represent mean ± SEM. Comparisons were performed using ANOVA with Tukey multiple comparison test, and a P value of <.05 was considered significant. ∗∗∗∗P < .0001; ∗∗∗P < .001; ∗∗P < .01; ∗P < .05. ns, nonsignificant.