Age-related reactivation of an X-linked gene close to the inactivation centre in the mouse

Abstract

Summary: Age-related reactivation of an X-linked gene which maps close toXce, the X chromosome inactivation centre, has been observed. In five female mice which carried the X-linked coat colour geneMo^bloon the reciprocal translocation T(X;16)16H (Searle's translocation), and the wild-type gene on the normal X chromosome, and therefore expressed theMo^blophenotype due to the non-random inactivation characteristic of Searle's translocation, progressive darkening of the coat was observed as the animals aged. This is due to reactivation of the previously inactivated wild-type gene at theMolocus on the normal X chromosome. As theMolocus is located 4 cM distal toXce, the X chromosome inactivation centre, these observations provide evidence of age-related instability of inactivation of an X-linked gene close to the inactivation centre.