Platelet monoamine oxidase activity in subjects tested for Huntington's disease gene mutation.

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.