However, the pI value of the purified SM deacylase was different from our previous report using analytical IEF chromatography of a homogenate of the SC of AD skin, which detected pI values of SM deacylase, BGCase, aSMase, and aCDase of 4.2, 7.4, 7.0, and 5.7, respectively [55]. Here, SMPD1 is linked to Alzheimer disease.