Mice homozygous for the jaundiced mutation are very pale but not jaundiced at birth, but develop severe jaundice within hours of being born. They have severe microcytic hemolytic anemia, and most die by 4 days of age, even on a mixed background, but a single blood transfusion in the first days of life can foster survival of homozygotes. On a mixed C57BL/6J x WB/Re background transfused homozygotes generally survive to adulthood and are reported to have a mean life expectancy of 3.7 months. The hemolytic anemia phenotype of these adults includes decreased hematocrit, very low red blood cell count, reticulocytosis, microcytosis, bilirubinemia, extensive iron accumulation in the kidney, elevated blood urea nitrogen, hydronephrosis, hepatomegaly, splenomegaly of predominantly red pulp, and cardiomegaly, but less severe thrombosis than is found in mice homozygous for the mutation spherocytosis (Spna1sph). The erythrocytes are extremely fragile and have a very short lifespan and there is extramedullary hematopoiesis. Heterozygotes have a mild, well compensated anemia and the erythrocytes have a higher concentration of protoporphyrin, increased osmotic fragility, and a slightly reduced lifespan.
The jaundiced mutation, first described in 1959, arose spontaneously at The Jackson Laboratory in a 129/Sv inbred strain that was homozygous for pink-eyed dilution and segregating for albino and chinchilla. Jaundiced was backcrossed separately onto the C57BL/6J and WB/Re backgrounds by Seldon Bernstein and each congenic strain reached generation N27 in 1968. This strain reached generation N39 in 1978 and was later passed to Dr. Jane Barker. In 2001 embryos were generated for cryopreservation from C57BL/6J females bred to heterozygous males at generation N80.
|Gene Symbol and Name||Sptb, spectrin beta, erythrocytic|
|Strain of Origin||129/Sv|
|Molecular Note||A C-to-T transition mutation is present in the mutant transcript and produces a premature stop codon from an arginine codon 1160 in the part of the mRNA encoding repeat 9 of beta-spectrin at amino acid position 1160 (p.R1160*).|