Analysis of UBQLN1 variants in a Polish Alzheimer's disease patient: control series.

Late-onset Alzheimer's disease (LOAD) is the most common neurodegenerative disorder, and has a complex etiology. Recently an intronic polymorphism in the ubiquilin 1 gene (UBQLN1) and a particular haplotype was reported to be associated with LOAD. We investigated whether variants in UBQLN1 confer a risk for the disease in 407 Polish LOAD patients and 407 controls. We observed a weak association with the rs2781002 polymorphism, however, contrary to the initial reports, in our group the association was with the A allele. Risk estimation for AA versus GG genotypes showed that the AA genotype is a weak risk factor for AD (OR = 1.8, 95% CI = 1.1-3.1, p = 0.025). This effect was stronger in a group of LOAD patients without APOE4 allele. Haplotype analyses indicate that there is an increase of haplotypes with an A allele in the case group. Also, the specific haplotypes with the A allele that increase AD risk differ between the APOE4-positive and APOE4-negative pools. However, the association observed seems to be driven mostly by rare (<5%) haplotypes. Results suggest a need for additional association studies and in silico analysis of the UBQLN1 locus.