Both male and female mice are fertile and easy to breed, male or female transgenic mice can be produced either as transgene heterozygotes or homozygotes, which can live more than 1.5 years, and, when mated with an inducible Cre line of mice, bi-transgenic mice allow for investigator-controlled increased expression of DUX4-fl mRNA and protein resulting in FSHD-like muscle pathology [48]. This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.