This allele is a derivative of Tfamtm1Lrsn in which the loxP flanked sequences were removed in the germline by Cre mediated recombination. Mice carrying the Tfamtm1Lrsn allele were mated to mice carrying the TgN(ACTB-Cre)2Mrt transgene to produce progeny in which the loxP flanked sequences were deleted. (J:46387)