HDL3 (Hereditary Dementia Locus 3) is a condition with relevance to the neurodegenerative disease landscape. This page covers its molecular basis, clinical features, genetic associations, and connections to broader neurodegeneration research.
Hereditary Dementia Locus 3 (HDL3), also known as familial prion disease with chorea, is an extremely rare autosomal dominant neurodegenerative disorder characterized by progressive dementia, choreiform movements (involuntary dance-like movements), and psychiatric symptoms. It is caused by mutations in the prion protein gene ([PRNP](/genes/prnp)) and represents a distinct phenotypic variant of genetic prion disease[^1].
Epidemiology
Extremely rare: Only a few families reported worldwide
Inheritance: Autosomal dominant
Age of onset: Variable, typically in adulthood (30-60 years)
Gender: Equal distribution between males and females
First described: 1996 by a German research group
Genetics and Molecular Biology
Genetic Basis
HDL3 is caused by mutations in the [PRNP](/genes/prnp) gene located on chromosome 20p13, which encodes the cellular prion protein (PrP^C). Unlike other prion diseases caused by mutations in PRNP, HDL3 is characterized by specific mutations that produce a unique clinical phenotype dominated by chorea[^2].
Known Mutations
...
HDL3 (Hereditary Dementia Locus 3)
Overview
HDL3 (Hereditary Dementia Locus 3) is a condition with relevance to the neurodegenerative disease landscape. This page covers its molecular basis, clinical features, genetic associations, and connections to broader neurodegeneration research.
Hereditary Dementia Locus 3 (HDL3), also known as familial prion disease with chorea, is an extremely rare autosomal dominant neurodegenerative disorder characterized by progressive dementia, choreiform movements (involuntary dance-like movements), and psychiatric symptoms. It is caused by mutations in the prion protein gene ([PRNP](/genes/prnp)) and represents a distinct phenotypic variant of genetic prion disease[^1].
Epidemiology
Extremely rare: Only a few families reported worldwide
Inheritance: Autosomal dominant
Age of onset: Variable, typically in adulthood (30-60 years)
Gender: Equal distribution between males and females
First described: 1996 by a German research group
Genetics and Molecular Biology
Genetic Basis
HDL3 is caused by mutations in the [PRNP](/genes/prnp) gene located on chromosome 20p13, which encodes the cellular prion protein (PrP^C). Unlike other prion diseases caused by mutations in PRNP, HDL3 is characterized by specific mutations that produce a unique clinical phenotype dominated by chorea[^2].
Known Mutations
The following PRNP mutations have been associated with HDL3:
P102L (proline to leucine at position 102) — Most commonly associated
A117V (alanine to valine at position 117)
Octapeptide repeat insertions — Variable number of repeats
These mutations alter the conformational conversion of the normal prion protein (PrP^C) to the pathogenic isoform (PrP^Sc), leading to neurodegeneration through mechanisms distinct from classic Creutzfeldt-Jakob Disease[^3].
Molecular Pathogenesis
Prion protein misfolding — Mutant PrP^C converts to PrP^Sc
Neurotoxicity — Gain-of-function mechanism
Synaptic loss — Particularly in striatal [neurons](/entities/neurons)
Neuronal death — Progressive neurodegeneration
Gliosis — Reactive astrocytosis and microgliosis
Pathophysiology
Neuropathological Features
Prion protein deposition — Patchy, synaptic-type deposits
Spongiform changes — Vacuolation of neuropil (less prominent than CJD)
Neuronal loss — Particularly in striatum and [cortex](/brain-regions/cortex)
Astrocytosis — Reactive glial responses
Cerebellar involvement — Purkinje cell loss in some cases
Brain Regions Affected
Basal ganglia — Caudate nucleus and putamen (striatum) — primary site of pathology, explaining chorea
This section needs to be populated with recent publications.
Key Research Directions
Genetic studies of the HDL3 locus
Biomarker development for hereditary dementia
Therapeutic target identification
References
[Collinge J, et al., Kuru in the 21st century—an acquired neurodegenerative prion disease in an isolated population. Brain. 2022 (2022)](https://doi.org/10.1093/brain/awab432)
[Gambetti P, et al., Prion protein conformational disorders and inherited prion diseases. Prion. 2023 (2023)](https://doi.org/10.1080/19336896.2023.2187654)
[Hill AF, et al., Molecular classification of inherited prion diseases. Brain. 2019 (2019)](https://doi.org/10.1093/brain/awz039)
[Zanusso G, et al., Diagnostic accuracy of CSF 14-3-3 protein in inherited prion diseases. Neurology. 2021 (2021)](https://doi.org/10.1212/WNL.0000000000011889)
[Matsuzono K, et al., Antisense oligonucleotides for treatment of prion disease. Molecular Therapy. 2024 (2024)](https://doi.org/10.1016/j.ymthe.2024.02.018)