Ostm1^om

The omi mutation was discovered because of high post-weaning lethality observed only after five generations of backcrossing to the original inbred strain in a line of mice bearing an unrelated, dominant ENU-induced mutation. It was mapped to a ~12 Mb region of Chr 10 containing ~100 genes including Ostm1, mutations of which are associated with a similar constellation of phenotypes in mice and humans. Crosses of omi and Ostm1gl mice demonstrated failure of the two mutations to complement each other. No causative lesion was identified by sequence analysis of the Ostm1 coding sequence, 5' and 3' UTRs and ~500 bp of upstream DNA. Immunoblot analysis of brain homogenates using an anti-OSTM1 antibody revealed levels of the major protein isoform in homozygous omi mice to be lower than in omi heterozygotes, but higher than in Ostm1gl homozygotes, consistent with the more severe phenotype of the latter. (J:195249)