DUAL BLASTOMERE ANALYSIS IMPROVES RELIABILITY OF PREIMPLANTATION TREMBLER MOUSE DIAGNOSIS

Dual blastomere biopsy and independent blastomere analysis dramaticall y improved preimplantation diagnostic reliability as confirmed by test ing the remaining biopsied eight-cell mouse embryo. The autosomal domi nant trembler mouse point mutation was selected as a model for human p reimplantation diagnosis because: (1) single cell assay failure is pre dicted to be the highest when testing autosomal dominant mutations; (2 ) point mutations represent the most common of all mutation categories and the most demanding mutation to assay reliably; and (3) the trembl er mouse point mutation in peripheral myelin protein 22 (Pmp22) is a m odel of human Charcot-Marie-Tooth type 1A disease. Mathematical models predict our experimental results assuming amplification of 80% of eac h target allele as well as trembler sperm DNA contamination in 1 of 44 normal biopsied single blastomeres. Single blastomere analysis correc tly pre dieted the genotype in only 84% of embryos that would have bee n implanted as normal. In contrast, when independent tests of both bio psied blastomeres agreed, test results were confirmed in 20 of 21 (95. 2%) of the remaining six-cell biopsied embryos designated as normal. T hus, biopsied six-cell embryo confirmation demonstrated that dual biop sied blastomere analysis improved test reliability remarkably.