Longevity of mice. Approximately 67% of T44 Tg mice survived until 9 months of age, but after crossbreeding with NFL−/− or NFH−/− mice, the survival went up to 90 or 78%, respectively. Longevity of mice was evaluated using cohorts of pups weaned at 3–4 weeks old because some mice died before 4 weeks from poor nursing. WT, n = 30; T44;NFL−/−,n = 20; T44;NFH−/−, n = 18; T44+/−, n = 24; T44+/+, n = 8.