The transmission rate of the lacI transgene from the Big Blue mouse

Since transgenic mice are being used to analyze somatic and germinal mutation rates in vivo, it is of interest to know to what extent these mice are normal or abnormal in any way. During experiments designed to compare the mutational response of the transgene and an endogenous gene, Big Blue mice hemizygous for the transgene were bred to create a hybrid mouse in which the comparisons could be made. The fraction of these mice that inherited the transgene was 37% rather than the Mendelian expectation of 50%.