In addition to studies estimating the increased risk of PD that is associated with MAPT H1, some studies have assessed associations between MAPT H1/H2 haplotypes and selected features, mainly cognitive function,14, 15, 16, 17, 18, 19 age at onset (AAO),20, 21, 22 PD subtype,23, 24 and progression.25 This evidence concerns the gene MAPT and Parkinson disease.