There is evidence that both environmental and genetic factors may play a role in the pathogenesis of Alzheimer's disease (AD). The amount of brain cholesterol, for instance, has been suggested to play a role in the development of the disease. Accordingly, the Apolipoprotein E (ApoE) ε4 allele has been identified as a major risk factor for the occurrence of AD. The product of the DHCR24/seladin-1 gene has enzymatic activity, which converts desmosterol into cholesterol. The expression of this gene, which confers protection against β-amyloid toxicity and from oxidative stress, is downregulated in AD vulnerable brain regions and it has been proposed as possibly involved in the pathogenesis of this disease. In this study, we evaluated the possible genetic contribution of the DHCR24/seladin-1 gene to Italian familial cases of AD. The exons 1–9 of this gene from 100 patients were subjected to mutation screening analysis. We identified a new C to T transition in exon 1 (Leu60Leu) and a previously described C to T transition in exon 7 (Ile342Ile-rs718265). Our preliminary results suggest the absence of an association between DHCR24/seladin-1 genotypes and AD in the Italian population. © 2007 Wiley-Liss, Inc.