RP1 and Alzheimer disease: In the five families with AD-RP (Families 1 to 5), five different heterozygous variants were identified, including four known RP1 variants (p.Arg677Ter, p.Gln678Ter, p.Lys867Ter, and p.Arg872ThrfsTer2) and one novel variant (p.Lys853Ter).