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Dopamine-beta-hydroxylase in patients with cystic fibrosis
Insights
Children with cystic fibrosis (CF) show lower plasma dopamine-beta-hydroxylase (DBH) enzyme activity. This reduced DBH activity in CF patients does not correlate with plasma catecholamines or explain autonomic dysfunction.
Area of Science:
- Biochemistry
- Pediatrics
- Genetics
Background:
- Cystic Fibrosis (CF) is a genetic disorder affecting multiple organs.
- Autonomic dysfunction is a potential complication in CF patients.
- Dopamine-beta-hydroxylase (DBH) is a key enzyme in catecholamine synthesis.
Purpose of the Study:
- To investigate plasma DBH enzymatic activity in children and adolescents with CF.
- To compare DBH levels in CF patients, their heterozygous parents, and healthy controls.
- To explore the relationship between DBH activity and plasma catecholamine levels in CF.
Main Methods:
- Enzymatic activity of plasma DBH was measured.
- Plasma norepinephrine and dopamine levels were assessed.
- Statistical analyses (t-tests, correlation) were performed to compare groups and variables.
Main Results:
- Significantly lower DBH levels were observed in CF patients compared to healthy controls (P < 0.01).
- No significant correlation was found between DBH activity and plasma norepinephrine or dopamine levels in CF patients.
- CF patients exhibited elevated plasma dopamine levels compared to controls.
Conclusions:
- Reduced plasma DBH activity in CF patients is a distinct finding.
- The observed DBH differences do not explain the elevated plasma dopamine or autonomic dysfunction in CF.
- Further research is needed to understand the mechanisms of catecholamine dysregulation in CF.
Abstract:
The enzymatic activity of plasma dopamine-beta-hydroxylase (DBH) was determined in 92 children/adolescents with cystic fibrosis, in 25 parents (heterozygotes) of these patients and in 68 healthy controls. Statistically significant (P less than 0.01) lower DBH levels were found in cystic fibrosis patients (17.9 +/- 1.4 mumol/min per 1, SEM) compared to the controls (25.5 +/- 2.1 mumol/min per 1). In 37 patients plasma norepinephrine and dopamine levels were compared to the enzymatic activity, no significant correlation between these variables being shown (r = -0.134 for norepinephrine; r = 0.159 for dopamine). However, due to the large variability of DBH within the groups and due to the lack of relationship of this enzymatic activity to plasma catecholamines, it is concluded that these differences may neither account for the observed elevation of plasma dopamine in cystic fibrosis patients (0.94-6.73 nmol/l vs. 0.01-0.986 nmol/l for controls) nor for their putative autonomic dysfunction.