ITM2B and ABri amyloidosis: Thus, to study familial Danish dementia (FDD) and familial British dementia (FBD), 15 years ago, we generated mice carrying the pathogenic Danish and British dementia mutations (integral membrane protein 2B [ITM2b]; Itm2bD and Itm2bB mice) into the Itm2b mouse gene (1, 2, 3).