Association between cathepsin D polymorphism and Alzheimer's disease in a Chinese Han population

Cathepsin D (CTSD) is an intracellular aspartyl protease, which is active in the endosomal/lysosomal system. CTSD may play a role in Alzheimer's disease (AD) through cleaving the amyloid precursor protein into beta-amyloid peptide and degrading tau protein into fragments. A functional polymorphism in exon 2 of the cathepsin D gene (C-->T, Ala224Val) has recently been reported to increase the risk for AD in some of the Caucasian populations, with a significant overrepresentation of the T allele, but these reports have not been universally duplicated. We performed an association study between CTSD polymorphism and AD in 156 sporadic AD patients and 183 controls of Chinese Han ethnicity. Our data revealed that the distribution of CTSD genotypes and alleles was similar in patients and controls. No direct association was found between CTSD polymorphism and AD risk. There might be a weak synergistic interaction between CTSD T and APOEepsilon4 allele in increasing the risk for developing AD.