F8 and hemophilia A: A study assessing the bleeding phenotypes of various FVIII knock-out (and wild-type)mouse strains in the tail-tip bleeding model revealed marked differences not onlybetween mouse strains, but between substrains and between the sexes.6 Haemophilia A mice (FVIII−/−) on a BALB/c background showed amilder haemophilic phenotype (blood loss) than FVIII−/− mice on a C57BL/6background.