Due to the limited amount of genetic material available in pre-implantation embryos, a nested PCR strategy was developed to yield reliable genotyping information (Figure 4). Whole embryos were first digested in 20 μL of proteinase K buffer (see below). The lysate was then divided in two, with half (10 μL) being used in the amplification of the wild-type allele and the remaining 10 μL in the amplification of the mutant allele.