Survival of WEPO mice. (A) Growth of a single litter of 6 mice, including wild-type (c-Kit^W/+) (•), lethal c-Kit^W/W (▪), and WEPO (c-Kit^W/WEPO-tg) (▴) mice. The weight of each mouse was determined daily for 3 weeks. (B) Kaplan-Meier plot for the survival of WEPO mice (n = 24) and viable c-Kit-deficient mice (n = 238) (Vickid; a viable c-Kit^W/W line distinct from WEPO8). Of all WEPO mice, approximately 40% survived long term. In the Vickid mouse colony, the overall survival of all white (c-Kit^W/W) pups is approximately 15%.