RARE SPECIES INBREEDING PROBLEM: “They lose fecundity (often due to increasing homozygosity of deleterious genes) … The new genomic editing techniques should be able to restore heterozygosity pretty easily in living genomes. It may even be possible to revive “extinct alleles” from museum specimens or fossils.”
http://e360.yale.edu/feature/the_case_for_de-extinction_why_we_should_bring_back_the_woolly_mammoth/2721/