Here, we describe a nonsense haplotype in PRNP associated with clinical 
Alzheimer's disease. The patient presented an early-onset of cognitive decline 
with memory loss as the primary cognitive problem. Whole-exome sequencing 
revealed a nonsense mutation in PRNP (NM_000311, c.C478T; p.Q160*; rs80356711) 
associated with homozygosity for the V allele at position 129 of the protein, 
further highlighting how very similar genotypes in PRNP result in strikingly 
different phenotypes.