Life-span and the inheritance of longevity of inbred mice.

Measures of life-span were obtained for male and female A/J, BALB/cJ, C57BL/6J, and DBA/2J inbred mouse strains and the six possible hybrid combinations (N equals 500, 10 groups, 25 male and 25 female per group). C57BL/6J mice were long lived, while A/J, BALB/cJ and DBA/2J mice were short lived, with the exception of female BALB/cJ mice, which lived as long as C57BL/6J mice. Female BALB/cJ and two female hybrid mouse groups with a BALB/cJ parent lived longer than males, but significant sex differences were not obtained for other groups. In general, the mode of inheritance of longevity was overdominant. For a second study (N equals 400) of the longevity of A/J and C57BL/6J strains and F1 and F2 hybrids it was estimated that one genetic factor was associated with longevity and the coefficient of genetic determination for longevity was estimated as between .48 and .79.