P21 gene variation and late-onset Alzheimer's disease in the Italian population

Background: Variation at the cyclin-dependent kinase inhibitor gene P21 in a patient sample of the Italian population was investigated in search of genetic factors potentially involved in sporadic late-onset Alzheimer’s disease (AD). Methods: Two single nucleotide polymorphisms (SNPs) were studied in this gene: a C>A transversion at codon 31 (ser>arg) in exon 2 (RS1801270) and a C>T transition occurring 20 bp downstream from the stop codon of exon 3 (RS1059234). Results: The odd ratios were: RS1801270 A allele = 0.62 (95% CI = 0.33–1.18; p = 0.14); RS1059234 T allele = 0.57 (95% CI = 0.33–0.98; p = 0.04). In addition, a longer duration of disease was found with genotypes carrying the RS1059234 T allele (4.3 ± 2.5 years) than with those not carrying it (3.3 ± 2.1 years) (p = 0.001). Conclusion: In the present sample, one of the two SNPs seems in some way related to AD, since carriers of one allele were slightly protected against AD onset.