Diminished expression of Lynx1 and Lypd6b [28] was recently reported in the hippocampal neurons of 2xTg-AD mice (a model of the early stage of AD with hyperexpression of mutant presenilin-1 (PS1-dE9) and chimeric APP with Swedish mutation K595N/M596L [29]). Here, PSEN1 is linked to Alzheimer disease.