Splenomegaly in the GATA-1.05 heterozygous mutant female mice. (A) Spleens were removed from wild-type (upper) andGATA-1.05 heterozygous (lower) littermates after genotyping and hematocrit screening of animals. Note that the spleen of theGATA-1.05 heterozygous mouse is markedly enlarged and is somewhat pink as compared with the dark red spleen from the wild-type mouse. (B) Sizes of the spleens from 6 wild-type (wt) and 22 heterozygous mutant (+/GATA-1.05) female mice. +/− b shows the spleen weights of the biopsied 8- to 12-week-old healthyGATA-1.05 heterozygous mice (those listed in Table 1). +/− a indicates mice that were found dead whose spleen weights were determined upon necropsy. (○) Mice no. 12 through 14 of Table 1 are indicated.