To analyze rare variants that significantly impact disease onset, sequencing analysis of many individuals' genomic DNA is essential. While whole-genome sequencing—analyzing the entire sequence of one person's genomic DNA—cost over 100 million dollars around 2,000, it has become very affordable today, costing less than 1,000 dollars. However, analyzing tens of thousands of individuals remains challenging. Therefore, it is still needed to analyze specific genes and genome regions. While various approaches have been proposed, we applied multiplex PCR, a classical technique amplifying multiple regions simultaneously to develop a method where the first PCR amplifies around 1,000 sites simultaneously, and the subsequent second PCR adds sequences identifying each individual. A major strength of this method is that, using dispensing equipment like that shown in the figure below, it enables the preparation of samples for next-generation sequencer analysis of thousands of individuals at once.

Initially, this method was used for fine mapping to analyze genes identified as candidates in genome-wide association studies( Nat Commun. 2018;9:4083 , Ann Rheum Dis. 2019;78:1062-1069 , etc). Since 2015, it has been applied to analyses focusing on hereditary cancers ( see the Cancer page ). This method has broad applicability. Dr. Taisei Mushiroda , a pharmacogenetics specialist at the same research center, constructed a panel targeting genes specialized in drug metabolism ( Drug Metab Pharmacokinet. 2021;37:100370 ). Furthermore, as an application for analyzing somatic mutations, collaborative research was conducted with Dr. Fumihiko Ishikawa ( Nat Cancer. 2021;2:340-356 ) from the same research center and Professor Seishii Ogawa ( Nat Med. 2021;27:1239-1249 )from Kyoto University. We have also collaborated on reports to clarify the characteristics of pathogenic variants in Japanese individuals with retinitis pigmentosa, an inherited eye disease ( J Med Genet. 2019;10:662-670 , etc). Furthermore, we have extended this work to research involving dogs and cats conducted in our laboratory ( see the Animals page ).