We studied the association between polymorphisms of genes coding for
dopamine D(2) (DRD2),
dopamine D(3) (DRD3),
serotonin 2(a) (HTR2A), and
serotonin 2(c) (HTR2C) receptors and
Antipsychotic-Induced
Parkinsonism (AIP), rigidity,
bradykinesia, and
rest-tremor in African-Caribbeans treated with
antipsychotics. Polymorphisms of DRD2 (-141CIns/Del, TaqIA, 957C > T), DRD3 (Ser9Gly), HTR2A (-1438A > G, 102T > C, His452Tyr), and HTR2C (-759C > T, Cys23Ser) genes were determined according to standard protocols. The Unified
Parkinson Disease Rating Scale was used for the measurement of AIP, rigidity,
bradykinesia, and
rest-tremor. Chi-squared or Fisher's exact tests were applied for the association analyses. The t-test was applied for continuous data. Ninety nine males and 27 females met the inclusion criteria (Schizophr Res 1996, 19:195). In males, but not in females, there were significant associations between -141CDel-allele carriership (DRD2) and rigidity (Fisher's Exact Test: P = 0.021) and between 23Ser-allele carriership (HTR2C) and
bradykinesia (P = 0.026, chi(2) = 5.0) or AIP (P = 0.008, chi(2) = 7.1).
Rest-tremor was not associated with any of the polymorphisms studied. Analyses of the age,
chlorpromazine equivalents,
benztropine equivalents, the number of patients using
anticholinergic medication, and the utilization patterns of the
antipsychotic medication did not show statistically significant differences between patients with and without AIP, rigidity,
bradykinesia,
rest-tremor. Conducting the analysis without gender stratification did not affect our findings considerably, except for the association between
bradykinesia and 23Ser-allele which failed to reach statistical significance in the total sample (P = 0.0646, chi(2) = 3.41). Since AIPs subsymptoms (rigidity,
bradykinesia, and
rest-tremor) may differ pharmacogenetically, our data strongly support symptom-specific analysis of AIP. However, further research is warranted to confirm our findings.