Preimplantation diagnosis of the β1 integrin knockout mutation as a model for aneuploid gene testing

Abstract.

The autosomal β1 integrin knockout mouse mutation was selected as a model to experimentally determine preimplantation diagnosis test reliability for autosomal gene deletions and duplications. In experiment 1, which analyzed 198 individually disaggregated single blastomeres, the observed test frequencies matched the mathematically predicted frequencies calculated from the independently derived values of 90% normal allele amplification, 92% mutant allele amplification, 4% alternate allele contamination, and 4% failure to transfer amplifiable target DNA into the PCR reaction mix. This experiment correctly predicted a normal embryonic phenotype in 143 (99.3%) of the 144 phenotypically normal autosomal recessive results. Experiment 2 compared single biopsied blastomere test results to test results on the remaining embryonic cells cultured 1 week until trophoblast outgrowth. Single biopsied blastomere analysis correctly predicted a normal autosomal recessive phenotype in 87 (98%) of the 89 embryos that would have been selected for implantation. Experiment 3 compared the PCR results of two biopsied blastomeres tested independently to the PCR result from the remaining cultured blastomeres to improve test reliability. Given that embryos would have been implanted only when two normal results were obtained, 17 of 17 phenotypically normal embryos would have been implanted from among the 44 embryos tested. These experiment 3 results are consistent with the mathematical prediction that about 99.9% of embryos implanted with two unaffected biopsied blastomere results would have had a phenotypically normal genotype.