SORL1 mutations in early- and late-onset Alzheimer disease.
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ABSTRACT: Objective
To characterize the clinical and molecular effect of mutations in the sortilin-related receptor (SORL1) gene.Methods
We performed whole-exome sequencing in early-onset Alzheimer disease (EOAD) and late-onset Alzheimer disease (LOAD) families followed by functional studies of select variants. The phenotypic consequences associated with SORL1 mutations were characterized based on clinical reviews of medical records. Functional studies were completed to evaluate β-amyloid (Aβ) production and amyloid precursor protein (APP) trafficking associated with SORL1 mutations.Results
SORL1 alterations were present in 2 EOAD families. In one, a SORL1 T588I change was identified in 4 individuals with AD, 2 of whom had parkinsonian features. In the second, an SORL1 T2134 alteration was found in 3 of 4 AD cases, one of whom had postmortem Lewy bodies. Among LOAD cases, 4 individuals with either SORL1 A528T or T947M alterations had parkinsonian features. Functionally, the variants weaken the interaction of the SORL1 protein with full-length APP, altering levels of Aβ and interfering with APP trafficking.Conclusions
The findings from this study support an important role for SORL1 mutations in AD pathogenesis by way of altering Aβ levels and interfering with APP trafficking. In addition, the presence of parkinsonian features among select individuals with AD and SORL1 mutations merits further investigation.
SUBMITTER: Cuccaro ML
PROVIDER: S-EPMC5082932 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
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Project description:ImportanceAutosomal dominant Alzheimer disease (ADAD) is caused by rare genetic mutations in 3 specific genes in contrast to late-onset Alzheimer disease (LOAD), which has a more polygenetic risk profile.ObjectiveTo assess the similarities and differences in functional connectivity changes owing to ADAD and LOAD.Design, setting, and participantsWe analyzed functional connectivity in multiple brain resting state networks (RSNs) in a cross-sectional cohort of participants with ADAD (n = 79) and LOAD (n = 444), using resting-state functional connectivity magnetic resonance imaging at multiple international academic sites.Main outcomes and measuresFor both types of AD, we quantified and compared functional connectivity changes in RSNs as a function of dementia severity measured by the Clinical Dementia Rating Scale. In ADAD, we qualitatively investigated functional connectivity changes with respect to estimated years from onset of symptoms within 5 RSNs.ResultsA decrease in functional connectivity with increasing Clinical Dementia Rating scores were similar for both LOAD and ADAD in multiple RSNs. Ordinal logistic regression models constructed in one type of Alzheimer disease accurately predicted clinical dementia rating scores in the other, further demonstrating the similarity of functional connectivity loss in each disease type. Among participants with ADAD, functional connectivity in multiple RSNs appeared qualitatively lower in asymptomatic mutation carriers near their anticipated age of symptom onset compared with asymptomatic mutation noncarriers.Conclusions and relevanceResting-state functional connectivity magnetic resonance imaging changes with progressing AD severity are similar between ADAD and LOAD. Resting-state functional connectivity magnetic resonance imaging may be a useful end point for LOAD and ADAD therapy trials. Moreover, the disease process of ADAD may be an effective model for the LOAD disease process.
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