The type II integral membrane (ITM2) protein family consists of three members ITM2A (also designated E25), ITM2B and ITM2C. ITM2A expression is high in osteogenic and lymphoid tissues, while both ITM2B and ITM2C are expressed in brain. Mutations in the ITM2B gene can lead to familial British dementia (fbd), and autosomal dominant disease characterized by progressive dementia, spasticity, and cerebellar ataxia, or familial Danish dementia (fdd), an autosomal dominant disorder characterized by cataracts, deafness, progressive ataxia, and dementia. The ITM2A 263-amino acid protein contains an N-terminal cytosolic domain, an uncleaved signal anchor sequence, and a tyrosine-rich C-terminal domain. Human ITM2A shares 91% homology with mouse ITM2A.