As part of this 7-year study (2003–2010), we screened DNA from 28 PSACH patients for mutations in COMP, 77 patients (suspected AD-MED and variants) for mutations in COMP, MATN3, and the three type IX collagen genes (COL9A1, COL9A2, and COL9A3), and 22 patients for mutations in SLC26A2 (suspected rMED). The gene discussed is MATN3; the disease is Alzheimer disease.