Deer mice with a compensated hemolytic syndrome caused by hereditary spherocytosis were placed in a controlled temperature room at 35 C. Severe anemia, red cell fragmentation, increased osmotic fragility, occasional jaundice and hemoglobinuria were observed. The spleen enlarged and the erythropoietic bone marrow expanded. Reticulocytes fell markedly early during heat exposure, but in survivors soon increased to levels higher than those observed prior to experiment. Mortality from the severe acceleration of the preexisting hemolysis was high. Control nonspherocytic deer mice subjected to an identical temperature showed only a mild drop of hemoglobin and slight elevation of reticulocytes.
Since hereditary spherocytosis in deer mice in a temperate climate is compatible with good health, these findings provide a further illustration of interaction of a particular environmental insult with a specific genotype in the pathogenesis of hereditary disease.