Normoblastosis homozygotes have a severe normocytic hypochromic anemia and can be identified at birth, or soon thereafter, by their bright orange color, which fades as they mature. They have elevated serum bilirubin and greatly increased fecal urobilinogen and the serum and urine remain highly colored even as the overall body color fades. Homozygotes are smaller than their wildtype and heterozygous siblings and display hepatomegaly, cardiac hypertrophy, marrow hyperplasia, leukocytosis, pronounced splenomegaly and enlarged lymph nodes. Nevertheless, the majority of homozygotes survive to adulthood. Immature red blood cells can be found in high numbers in the peripheral blood, and red cells are hypchromic although of normal or slightly elevated mean cell volume. In addition to hematopoietic defects this ankyrin 1 hypomorph also displays Purkinje cell degeneration such that there is a 50% loss of Purkinje cells at 6 months of age and concomitant tremors and unbalanced gait (Peters et al., 1991). More than half of homozygotes on a WBB6F1 hybrid background have been reported to develop calcium bilirubinate pigment gallstones after 6 months of age, with luminal gallstones occurring twice as frequently in females as in males (Trotman et al., 1980).
