Mutation screen of the cone-specific gene, CLUL1, in 376 patients with age-related macular degeneration.

Clusterin is a secreted glycoprotein expressed ubiquitously in many tissues that appears to function as a molecular chaperone capable of protecting stressed proteins. It is upregulated in many different forms of neurodegeneration and is thought to represent a defense response against neuronal damage. Clusterin has been found to be a common protein identified in drusen preparations isolated from the retina of donor eyes of patients with age-related macular degeneration (AMD), the leading cause of blindness in the elderly population of developed countries. A retina-specific clusterin-like protein (CLUL1) showing nearly 25% identity to clusterin at the protein level was recently cloned and shown to be expressed specifically in cone photoreceptor cells. For these reasons, we investigated CLUL1 as a candidate gene for AMD. A mutation screen of the entire coding region of the CLUL1 gene in 376 unrelated patients with AMD uncovered three sequence variations, one isocoding change and two intronic changes. One intronic change appears significantly less frequent in patients with the more severe forms of AMD than in control subjects, suggesting that this variant may reduce the risk for AMD or may be linked to a nearby variant that may reduce AMD risk. Variant alleles of the CLUL1 gene were found; however, none are considered pathogenic. None of the variants identified are predicted to create or destroy splice donor or acceptor sites based on splice-site prediction software.