ABCC9 and early-onset autosomal dominant Alzheimer disease: Studies that previously reported polymorphisms in GRN, TMEM106B and ABCC9 as risk factors for LATE‐NC + HS, obtained cases from brain banks and Alzheimer's Disease Centers 1, 8, 14, 16, which tend to oversample people with dementia and frequently lack sufficient numbers of the oldest old to test hypotheses in this age group.