| Type | MGI:General | Description | after 1 backcross to C57BL/6 (or N1 generation), 1/3 mice die by <150 days of age; N2 generation mice show 36% lethality with median age at death of ~87 days, while in the N3 generation, 50% mortality is seen at median age of 65 days and in the N4 generation, 100% of mice die with median age of 65 days |
