In a cohort of patients affected by RP/RCD originating from Western Sicily, we found a statistically significant (p-value = 0.0073) high prevalence of the RP1 c.2219C>G (p.Ser740*) pathogenic variant, proven to be causative in 33.3% of the 84 examined probands and 74% of the 25 clearly AD pedigrees. This evidence concerns the gene RP1 and Alzheimer disease.