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Completed

NCT Number: NCT07393113

CLarifying ABCB1's Role in Alzheimer's Disease

Alzheimer's disease is biologically defined by the accumulation of amyloid beta and tau protein, identified using cerebrospinal fluid biomarkers. The ABCB1 gene, which encodes P-glycoprotein involved in amyloid beta efflux across the blood-brain barrier, may influence Alzheimer's disease risk. We hypothesize that certain functional ABCB1 polymorphisms impair amyloid beta clearance, thereby promoting the development of biologically defined Alzheimer's disease.

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Key information

Conditions

Alzheimer Disease Brain Diseases Central Nervous System Diseases Dementia Mental Disorders Nervous System Diseases Neurocognitive Disorders Neurodegenerative Diseases Tauopathies

Age range

50 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Hôpital Lariboisière - Fernand Widal (AP - HP)

Paris, France

About this study

A case-control study comparing the distribution of three functional ABCB1 gene polymorphisms (3435C>T, 2677G>T/A, 1236C>T) in patients with biologically defined Alzheimer's disease versus neurological controls. We will also analyze the distribution of haplotypes derived from the combination of these three polymorphisms and investigate potential interactions between these polymorphisms and the APOE genotype, particularly the presence of the ε4 allele.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • age ≥ 50 years,
  • available cerebrospinal fluid biomarker results,
  • an available and usable DNA sample,
  • and consent for future research use within the biobank.

Exclusion criteria

  • the presence of an active non-degenerative neurological disorder (for example, multiple sclerosis, infections, or tumors),
  • and missing data regarding APOE genotyping or cardiovascular risk factors

Treatment and study plan

ABCB1 genotyping

Genetic

Genotyping of three single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T) associated with variation in P-glycoprotein activity, using DNA samples stored in a biobank.

Primary outcomes

  1. Allele and genotype frequencies of ABCB1 single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T)

    Time frame: Baseline (at the time of biological sampling and clinical assessment)

    Allele and genotype frequencies of the ABCB1 single nucleotide polymorphisms 3435C>T, 2677G>T/A, and 1236C>T, determined by genotyping from genomic DNA, will be compared between:

    • patients with biologically defined Alzheimer's disease (A+T+Nx), and
    • neurological control participants with a negative biomarker profile (A-T-N-). Data will be summarized as allele frequencies and genotype distributions in each group.

Secondary outcomes

  1. Haplotype frequencies of ABCB1 polymorphisms (3435C>T, 2677G>T/A, and 1236C>T)

    Time frame: Baseline (at the time of biological sampling and clinical assessment)

    Haplotype frequencies derived from the combination of the ABCB1 single nucleotide polymorphisms 3435C>T, 2677G>T/A, and 1236C>T, inferred from genotyping data, will be compared between:

    • patients with biologically defined Alzheimer's disease (A+T+Nx), and
    • neurological control participants with a negative biomarker profile (A-T-N-). Haplotypes will be summarized as frequency distributions within each group.

  2. Distribution of ABCB1 polymorphisms stratified by APOE ε4 carrier status

    Time frame: Baseline (at the time of biological sampling and clinical assessment)

    The distribution of ABCB1 single nucleotide polymorphisms (3435C>T, 2677G>T/A, and 1236C>T) will be assessed according to APOE ε4 carrier status (ε4 carriers vs non-carriers) in:

    • patients with biologically defined Alzheimer's disease (A+T+Nx), and
    • neurological control participants with a negative biomarker profile (A-T-N-). ABCB1 allele and genotype frequencies will be summarized within each APOE ε4 stratum.

Sponsors and collaborators

Lead sponsor

Assistance Publique - Hôpitaux de Paris

Other

Registry information

Official study title

CLarifying ABCB1's Role in Amyloid Efflux and Alzheimer's Disease Risk

Acronym: CLeAR-AD

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Feb 6, 2026
Registry last updated
Feb 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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