A role for the rare endogenous retrovirus β4 in development of Japanese fancy mice

Two coat-color mutations, nonagouti, which changes coat color from wild-type agouti to black, and piebald, which induces irregular white spotting, are the characteristics of Japanese fancy mouse strain JF1/Ms. In our Communications Biology article, we reported that insertion of a rare type of endogenous retrovirus β4 has caused both coat color mutations. Although there are some reports on the roles of β4 in the mouse genome, further studies on β4 will uncover new features of endogenous retrovirus sequences.