Association of genetic polymorphisms of claudin-1 with small vessel vascular dementia.

The most recent hypothesis of the development of small vessel vascular dementia (VaD) emphasises the role of blood-brain barrier (BBB) dysfunction. It is hypothesised that certain genetic polymorphisms of the BBB tight junction claudin-1 protein, in combination with adverse environmental risk factors, increase the risk of BBB dysfunction and small vessel VaD. In this case-control study, 97 control participants, with a mean Mini Mental State Exam (MMSE) score of 29.1, and 38 VaD participants were recruited and completed a questionnaire on their medical history and lifestyle factors. Blood was also collected and two single nucleotide polymorphisms (SNPs), rs17501010 and rs893051 of claudin-1 genotyping, were analysed by real-time polymerase chain reaction (PCR) assay. A significantly higher frequency of all rs893051 SNP genotypes (GC and CC) was found in the VaD population (OR=4.8, P=0.006 and OR=6, P<0.001 respectively). Patients with TT genotype of rs17501010 were also more likely to have VaD (OR=3.25, P=0.022). Stratification analysis revealed that having combined haplotype GC+CC of rs893051 and lipid disorders was associated with higher risk of VaD (OR=9.9, P<0.001). For patients with type 2 diabetes the odds ratio of VaD increased significantly in GC+CC genotypes of rs893051 (OR=12.57, P<0.0001) and GT+TT of rs17501010 (OR=5.33, P=0.01).