A recent study of 88 individuals with a family history of AD investigating hippocampal sub-region volumes found those with abnormal CSF β-amyloid, but normal CSF tau had increased right subiculum volumes, whilst abnormal CSF β-amyloid and abnormal CSF tau was associated with decreased right subiculum volume [21] suggesting the presence of tau deposition is important for hippocampal atrophy and has selective effects on certain subfields. The gene discussed is MAPT; the disease is hippocampal atrophy.