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Platelet monoamine oxidase activity in subjects tested for Huntington's disease gene mutation
M Markianos1, M Panas, N Kalfakis
1Athens University Medical School, Eginition Hospital, Neurologic Clinic, Athens, Greece. markian@otenet.gr
Abstract:
Monoamine oxidase activity (MAO) has been related to neuronal damage, since the oxidative deamination of biogenic amines produces free radicals that may enhance oxidative stress. Elevated enzyme activities in brain (MAO-A and MAO-B forms) and in platelets (MAO-B form) have been reported in several degenerative diseases, indicating that MAO activity may be involved in the disease progression. We estimated platelet MAO activity in a group of 59 patients (34 males) with HD, 20 subjects (7 males) at risk, and 29 (14 males) healthy subjects with positive family history for HD, categorized according to clinical features and the number of CAG repeat units (CAG-RN) at the Huntington gene. A group of 64 subjects (36 males) with negative family history for HD served as controls. In contrast to some previous studies, platelet MAO activities in both male and female patients (CAG-RN 40 to 62) with overt symptomatology, were not different compared to same sex control subjects. Subjects at risk (CAG-RN 39 to 52), though, showed significantly lower activities compared to same sex patients or controls. MAO activities seem to increase with disease progression, and tend to be higher in patients with dementia. The increases may be an epiphenomenon of disease pathology, but the possibility that an increase in the expression of the enzyme precedes the onset of the disease and contributes to enhanced oxidative stress should be considered in future longitudinal studies as a possible mechanism that accelerates disease progression.
Insights
Platelet monoamine oxidase (MAO) activity is not elevated in Huntington
Area of Science:
- Neuroscience
- Biochemistry
- Genetics
Background:
- Monoamine oxidase (MAO) activity is linked to neuronal damage through free radical production.
- Elevated MAO-A and MAO-B in the brain, and MAO-B in platelets, are implicated in neurodegenerative diseases.
- MAO activity's role in disease progression, particularly in Huntington's disease (HD), requires further investigation.
Purpose of the Study:
- To investigate platelet monoamine oxidase (MAO) activity in individuals with Huntington's disease (HD).
- To compare MAO activity across HD patients, at-risk individuals, and healthy controls.
- To explore the relationship between MAO activity, CAG repeat numbers, and disease progression in HD.
Main Methods:
- Platelet MAO activity was measured in 59 HD patients, 20 at-risk subjects, and 29 healthy controls with a positive family history.
- A control group of 64 subjects with no family history of HD was also included.
- Participants were categorized by clinical features and CAG repeat units (CAG-RN) in the Huntington gene.
Main Results:
- Platelet MAO activities in symptomatic HD patients (CAG-RN 40-62) did not differ from same-sex controls.
- Subjects at risk for HD (CAG-RN 39-52) exhibited significantly lower MAO activities compared to patients and controls.
- MAO activity appeared to increase with disease progression and was higher in patients with dementia.
Conclusions:
- Platelet MAO activity is not elevated in symptomatic HD patients compared to controls.
- Reduced MAO activity in at-risk individuals suggests a potential early biomarker.
- The observed increase in MAO activity with disease progression may be linked to oxidative stress and warrants further longitudinal study.
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