The transgenic construct consists of a 370kb YAC insert that includes the entire human FXN gene with GAA triplet repeat sequences, and was injected into fertilized CBA X C57BL/6 hybrid fertilized oocytes. Founder line YG8 was established, carrying 2 tandem copies of the human FXN gene with two GAA trinucleotide repeat sequences of 82 and 190 repeats. This line displayed a transmission rate of 52% to offspring.