PSEN1 and dementia: The team described a Colombian brother and sister carrying a rare variant in the RELN gene (H3347R coined as RELN-COLBOS after the Columbia-Boston biomarker research study) who showed delayed onset of autosomal-dominant Alzheimer disease despite carrying the PSEN1 E280A mutation known to cause mild cognitive impairment (MCI) by around age 44 and AD type dementia by age 49.1