Biomarker Analysis for GBA Associated Parkinson's Disease
| Status: | Recruiting |
|---|---|
| Conditions: | Parkinsons Disease, Metabolic |
| Therapuetic Areas: | Neurology, Pharmacology / Toxicology |
| Healthy: | No |
| Age Range: | 50 - Any |
| Updated: | 1/23/2019 |
| Start Date: | February 1, 2018 |
| End Date: | July 2020 |
| Contact: | Renuka Limgala, PhD |
| Email: | rlimgala@ldrtc.org |
| Phone: | 2407155382 |
Biomarker Analysis for Parkinson's Disease in Subjects With Glucocerebrosidase Mutations
The primary aim of the study is to conclusively demonstrate the possibility of using the
following molecules, α-Synuclein, LRRK2 and Parkin individually or in combination as
biomarkers for Parkinson's disease (PD) progression in patients/ carriers of Gaucher disease
(GD). All the assays will be performed only using peripheral blood, thus the identification
of a peripheral marker that can be used in both diagnosis and prognosis of the disease and
symptom severity would lead to a fast, efficient and reliable assay that can be performed on
an easily accessible tissue type outside of the brain. It is now known that patients with GD,
even carriers with one mutated GBA gene (OMIM 606463) are at a higher risk for developing PD,
and at an earlier age. In an attempt to assess whether GBA alterations would also impact
α-Synuclein and Parkin metabolism in humans we plan to investigate the expression at both
molecular and protein level in the peripheral blood mononuclear cells (PBMCs).
following molecules, α-Synuclein, LRRK2 and Parkin individually or in combination as
biomarkers for Parkinson's disease (PD) progression in patients/ carriers of Gaucher disease
(GD). All the assays will be performed only using peripheral blood, thus the identification
of a peripheral marker that can be used in both diagnosis and prognosis of the disease and
symptom severity would lead to a fast, efficient and reliable assay that can be performed on
an easily accessible tissue type outside of the brain. It is now known that patients with GD,
even carriers with one mutated GBA gene (OMIM 606463) are at a higher risk for developing PD,
and at an earlier age. In an attempt to assess whether GBA alterations would also impact
α-Synuclein and Parkin metabolism in humans we plan to investigate the expression at both
molecular and protein level in the peripheral blood mononuclear cells (PBMCs).
The GBA (OMIM 606463) gene codes for beta-glucocerebrosidase, a lysosomal enzyme. Disease
causing mutations in both alleles of GBA gene cause Gaucher disease (GD) while mutations in
one allele lead to Gaucher carrier status. It has been shown recently that patients with GD,
even carriers with one mutated GBA gene are at a higher risk for developing Parkinson disease
(PD), and at an earlier age, and that the GBA mutations comprise the primary genetic risk
factor in the development of PD and other forms of parkinsonism. However, there are no
biomarkers to determine the diagnosis of PD, especially in the early and minimally
symptomatic or asymptomatic stage. The progression of PD in subjects with a mutation in the
GBA gene can currently not be determined. In some cellular and animal models,
glucocerebrosidase alterations were shown to impact the metabolism of other proteins
implicated in PD pathology. α-Synuclein and Parkin, encoded by SNCA and PARK2 respectively,
are implicated in rare genetic forms of parkinsonism. α-Synuclein aggregates are seen in
cells of the central and peripheral nervous system and is considered to be the pathological
culprit in PD. Mutated glucocerebrosidase has been shown to be present in α-Synuclein
aggregates in postmortem brain samples from individuals with GBA mutations and PD.
α-Synuclein in addition, is shown to affect the solubility of Parkin in the cells. As an
attempt to assess whether GBA alterations would also impact α-Synuclein and Parkin metabolism
in humans in easily accessible cell types outside the brain, we propose to investigate the
expression at both molecular and protein level in the peripheral blood mononuclear cells
(PBMCs). The study we are proposing includes three cohorts: 1) Patients and carriers of
Gaucher disease with confirmed disease causing mutations in GBA gene who have developed
Parkinson's disease symptoms (GD-PD), 2) Patients and carriers of Gaucher disease with no
known Parkinson's symptoms (GD-nonPD) and 3) Non-Gaucher disease/healthy controls (HC). PBMCs
extracted from 3-5 ml peripheral blood will be used for intracellular staining for
α-Synuclein, LRRK2 and Parkin and then acquired on Flow cytometer (BD accuri). Lymphocytes
and monocytes will be analyzed for α-Synuclein, LRRK2 and Parkin expression. PBMCs will also
be used for RNA extraction and subsequent molecular analysis using qPCR. We have performed
these assays on a pilot study and observed an increase in α-Synuclein expression in
lymphocytes as well as monocytes. In addition we also noted a fraction of cells with very
high fluorescence indicating high expression of α-Synuclein potentially signifying
aggregation of this protein in that fraction of PBMCs. This observation was seen in only
subjects with GBA gene mutations who exhibit Parkinson symptoms. This was not seen in other
control groups. Since the assay utilized an easily accessible tissue type i.e., peripheral
blood and requires a very small amount (2-3 ml), this assay could be developed as a potential
biomarker for diagnosis and a disease progression indicator for Parkinson disease in subjects
with GBA gene mutations.
causing mutations in both alleles of GBA gene cause Gaucher disease (GD) while mutations in
one allele lead to Gaucher carrier status. It has been shown recently that patients with GD,
even carriers with one mutated GBA gene are at a higher risk for developing Parkinson disease
(PD), and at an earlier age, and that the GBA mutations comprise the primary genetic risk
factor in the development of PD and other forms of parkinsonism. However, there are no
biomarkers to determine the diagnosis of PD, especially in the early and minimally
symptomatic or asymptomatic stage. The progression of PD in subjects with a mutation in the
GBA gene can currently not be determined. In some cellular and animal models,
glucocerebrosidase alterations were shown to impact the metabolism of other proteins
implicated in PD pathology. α-Synuclein and Parkin, encoded by SNCA and PARK2 respectively,
are implicated in rare genetic forms of parkinsonism. α-Synuclein aggregates are seen in
cells of the central and peripheral nervous system and is considered to be the pathological
culprit in PD. Mutated glucocerebrosidase has been shown to be present in α-Synuclein
aggregates in postmortem brain samples from individuals with GBA mutations and PD.
α-Synuclein in addition, is shown to affect the solubility of Parkin in the cells. As an
attempt to assess whether GBA alterations would also impact α-Synuclein and Parkin metabolism
in humans in easily accessible cell types outside the brain, we propose to investigate the
expression at both molecular and protein level in the peripheral blood mononuclear cells
(PBMCs). The study we are proposing includes three cohorts: 1) Patients and carriers of
Gaucher disease with confirmed disease causing mutations in GBA gene who have developed
Parkinson's disease symptoms (GD-PD), 2) Patients and carriers of Gaucher disease with no
known Parkinson's symptoms (GD-nonPD) and 3) Non-Gaucher disease/healthy controls (HC). PBMCs
extracted from 3-5 ml peripheral blood will be used for intracellular staining for
α-Synuclein, LRRK2 and Parkin and then acquired on Flow cytometer (BD accuri). Lymphocytes
and monocytes will be analyzed for α-Synuclein, LRRK2 and Parkin expression. PBMCs will also
be used for RNA extraction and subsequent molecular analysis using qPCR. We have performed
these assays on a pilot study and observed an increase in α-Synuclein expression in
lymphocytes as well as monocytes. In addition we also noted a fraction of cells with very
high fluorescence indicating high expression of α-Synuclein potentially signifying
aggregation of this protein in that fraction of PBMCs. This observation was seen in only
subjects with GBA gene mutations who exhibit Parkinson symptoms. This was not seen in other
control groups. Since the assay utilized an easily accessible tissue type i.e., peripheral
blood and requires a very small amount (2-3 ml), this assay could be developed as a potential
biomarker for diagnosis and a disease progression indicator for Parkinson disease in subjects
with GBA gene mutations.
Inclusion Criteria:
The study will include
1. adult subjects age 21 or older with Gaucher disease with and without parkinsonism and
individuals from families with a Gaucher proband and a history of parkinsonism.
2. Controls will include unaffected siblings of patients with Gaucher disease and
subjects with sporadic PD, without glucocerebrosidase mutations, and healthy
volunteers who do not have a family history of parkinsonism or Gaucher disease.
Exclusion Criteria:
Subjects excluded from the study include those who:
1. present with severe cognitive deficits impairing decision making
2. are unable to or for whom it is medically unsafe to withdraw from their current
medications, such as subjects on SSRI s and other psychoactive drugs. The subjects on
SSRIs may be included in the study only with an approval from the prescribing
physician to discontinue their medications temporarily for the study.
3. are pregnant or nursing. All women of child bearing potential will undergo a pregnancy
test.
4. have a history of neurologic conditions such as stroke or any focal brain lesion that
may result in parkinonian manifestations. Individuals with such MRI findings will be
excluded from the study.
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