Another Fanca-deficient strain with a deletion of exons 1‒6 was constructed in two mouse strains, and it was found that the loss of Fanca exhibited reduced litter sizes in 129S6 strain, but infertility with almost all PGCs lost in fetal ovaries in C57BL/6 strain (Wong et al. 2003). This evidence concerns the gene FANCA and Infertility.