Tg-I278T Cbs−/− mice have severe hyperhomocysteinemia (HHcy) (plasma total Hcy = 272 ± 50 μM compared to 5.0 ± 2.6 μM in Cbs+/− siblings [28]), a 25% shorter life span (613 vs. 821 days) [27], and are characterized by a thin, smooth, shiny tail [29] and a reduced body weight [29]. Here, CBS is linked to hyperhomocysteinemia.