Universal strategy for preimplantation genetic testing for cystic fibrosis based on next-generation sequencing

We developed and applied a universal strategy for preimplantation genetic testing for all cystic fibrosis gene mutations (PGT-CF) based on next-generation sequencing (NGS).

A molecular protocol was designed to diagnose all CF mutations at preimplantation stage. The detection of CF mutations was performed by direct gene sequencing and linkage strategy testing 38 specific SNPs located upstream and inside the gene for PGT-CF. Seventeen couples at risk of CF transmission decided to undergo PGT-CF. Trophectoderm cell biopsies were performed on days 5-6 blastocysts. PGT for aneuploidy (PGT-A) was performed from the same samples. Tested embryos were transferred on further natural cycles.

PGT was performed on 109 embryos. Fifteen CF mutations were tested. PGT-CF and PGT-A were conclusive for, respectively, 92.7% and 95.3% of the samples. A mean of 24.1 SNPs was informative per couple. After single embryo transfer on natural cycle, 81.3% of the transferred tested embryos implanted.

The present protocol based on the entire CFTR gene sequencing together with informative SNPs outside and inside the gene can be applied to diagnose all CF mutations at preimplantation stage.