Novel inheritance of the murine severe combined anemia and thrombocytopenia (Scat) phenotype.

Abstract

The phenotype of the autosomal recessive mutation scat includes severe intermittent bleeding, depletion of platelets, and circulating anti-platelet antibodies. In this study, we have mapped the scat mutation to mouse chromosome 8 and shown that the immune component is a secondary consequence of the gene defect. Surprisingly, the phenotype of the scat/scat pups depends on the genotype of the mother. Maternal homozygosity prevents disease transmission; crosses between scat homozygotes produce few affected young, while the expected frequency is generated from normal (+/+) mice bearing scat/scat ovaries. The results suggest a novel method of maternal-fetal interaction that relies neither on transfer of maternal mitochondria nor on parental imprinting. We conclude that contribution from the maternal wild-type allele is required for expression of the scat phenotype in homozygotes.