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ObjectiveRecent studies have suggested that diminished Ccr5 functioning has an effect on synaptic plasticity and hippocampal memory in mouse models. CCR5-delta32, a 32-bp frameshift deletion in human CCR5 encoding a nonfunctional receptor, has been reported to have a protective effect against human immunodeficiency virus infection but its role as a modifier of neurodegenerative disease has been minimally explored. We investigated whether the CCR5-delta32 polymorphism could have an effect in the context of human neurodegenerative diseases.MethodsWe examined the frequency of the CCR5-delta32 polymorphism in a large and well-characterized cohort including 1425 patients with neurodegenerative dementias and 2032 controls.ResultsWe did not observe a significant association between the CCR5-delta32 polymorphism and any of the neurodegenerative diseases screened in this study. However, we observed an earlier age of onset among neurodegenerative disease patients carrying the CCR5-delta32 allele.ConclusionsAlthough our findings were inconclusive, the earlier age of onset observed among neurodegenerative disease patients carrying the CCR5-delta32 allele suggests that the deletion may have a detrimental effect in the context of neurodegeneration.

ObjectiveA rare variant in TREM2 (p.R47H, rs75932628) has been consistently reported to increase the risk for Alzheimer disease (AD), while mixed evidence has been reported for association of the variant with other neurodegenerative diseases. Here, we investigated the frequency of the R47H variant in a diverse and well-characterized multicenter neurodegenerative disease cohort.MethodsWe examined the frequency of the R47H variant in a diverse neurodegenerative disease cohort, including a total of 3058 patients clinically diagnosed with AD, frontotemporal dementia spectrum syndromes, mild cognitive impairment, progressive supranuclear palsy syndrome, corticobasal syndrome, or amyotrophic lateral sclerosis and 5089 control subjects.ResultsWe observed a significant association between the R47H variant and AD, while no association was observed with any other neurodegenerative disease included in this study.ConclusionsOur results support the consensus that the R47H variant is significantly associated with AD. However, we did not find evidence for association of the R47H variant with other neurodegenerative diseases.

Recently, Coppola and colleagues demonstrated that a rare microtubule-associated protein tau (MAPT) sequence variant, c.454G>A (p.A152T) significantly increases the risk of frontotemporal dementia (FTD) spectrum disorders and Alzheimer disease (AD) in a screen of 15,369 subjects. We describe clinical features of 9 patients with neurodegenerative disease (4 women) harboring p.A152T, aged 51 to 79 years at symptom onset. Seven developed FTD spectrum clinical syndromes, including progressive supranuclear palsy syndrome (n=2), behavioral variant FTD (bvFTD, n=1), nonfluent variant primary progressive aphasia (nfvPPA, n=2), and corticobasal syndrome (n=2); 2 patients were diagnosed with clinical AD. Thus, MAPT p.A152T is associated with a variety of FTD spectrum clinical presentations, although patients with clinical AD are also identified. These data warrant larger studies with clinicopathologic correlation to elucidate the influence of this genetic variant on neurodegenerative disease.