PSEN1 and Alzheimer disease: The importance of the EC in the AD pathological cascade has recently been underscored by the publication of a case report51 describing a member of the world's largest known kindred with autosomal dominant AD due to the PSEN1‐E280A mutation, who was additionally heterozygous for a rare mutation in the RELN gene encoding reelin and whose age of dementia onset was delayed by almost three decades compared to other kindred members.