Chris T.L. Chan from the Hong Kong Sanitorium & Hospital in China spoke at London Calling 2019 on “Long-read NGS guided preimplantation genetic testing for chromosomal structural rearrangement.” Chan presented a clinical scenario. They explained that short-read sequencing allowed the analysis of copy number variation from blood samples. Loss of copy can be identified with amniotic fluid. Chan spoke about the use of preimplantation genetic testing. Results can be interpreted to identify inheritance patterns of chromosomes and copy numbers. Because sequencing is used, breakpoints can be determined. However, short-read sequencing approaches may not provide enough information in some cases. In 2017, Chan began using Oxford Nanopore Technologies (ONT) and long-read whole genome sequencing. Chan and team studied ectrodactyly, a genetic disease with resulting missing fingers. Using the ONT MinION, they found the duplication of 683 kb! This information helped the team design PCR primers. Because ONT is not intended for clinical use, Chan and the team performed additional confirmatory assays. Chan also shared data from other cases and how they identify breakpoints with ONT. Information on carrier status can be provided to the family. With this information, the patients can decide how to proceed. Chan also shared that they are using Cas9 enrichment and ONT. Chan concluded that long-read sequencing can be used to improve pre-implantation genetic testing.
