COL9A2 and Alzheimer disease: Pseudoachondroplasia (PSACH; MIM# 177170) and multiple epiphyseal dysplasia (MED; MIM# 132400) are relatively common skeletal dysplasias that can be inherited as either autosomal dominant (PSACH and AD-MED) or recessive (AR-MED; rMED) conditions [Briggs and Chapman, 2002; Superti-Furga and Unger, 2007].