Phenotypic Characteristics of Zambian patients with Parkinson's Disease

Abstract

Objective: To describe the phenotypic characteristics of adult Zambian patients with newly diagnosed Parkinson's disease (PD) at University Teaching Hospital (UTH).
Background: The genetic basis of idiopathic Parkinson's disease is remains unknown. Little information is available regarding the genotype and phenotypic characteristics of PD among people of African origin.
Methods: Subjects with PD were recruited from the neurology clinic from January 2010, through April 2011. Parkinson's disease diagnosis was established according to standard criteria. Only ethnic Zambian patients were included to the study. The disease was considered familial when one or more first to third degree relatives were affected with PD. Extensive pedigree was constructed for all familial and sporadic cases. Unrelated healthy controls (spouses, volunteers) were free of PD and other movement disorders. Genomic DNA was extracted from peripheral blood leukocytes according to standard procedures from patients and controls, respectively.
Results: In total 46 patients for phenotype and 46 controls were matched with patients for age, gender, and area of residence. The mean age of patients at onset of the disease was 53.8 ±13.7years. Three patients had juvenile form PD and12 patients had early onset PD. In 31 patients the disease started after 50 years old. Tremor and bradykinesia were the most common initial symptoms. 26% had a history of first-and second-degree relatives affected with PD. Mean age were significantly lower in patients with familial PD (47.7±7.3) than sporadic disease (62,5±5.4) (p>0.001). In 8 families (66.6%) the disease had autosomal dominant and in 4 families (33.3%) autosomal recessive inheritance. Age at onset was significantly lower (27 years) in patients with autosomal recessive transmission than in patients with autosomal dominant inheritance. The disease duration was significantly longer in patients with autosomal recessive inheritance (11.2 years) than in patients with autosomal dominant inheritance (3 years).
Conclusions: This study represents phenotypic description of Zambian patients with PD recruited in clinical based manner. The majority of our patients were characterized tremor-dominant or akineticrigid types of the disease. Age at onset of PD was younger as compared to European population. The disease has both autosomal dominant and autosomal recessive inheritance. The familial aggregation of PD warrant further studies of genetic and environmental risk factors n the Zambian population.

Keywords: Phenotype, Parkinson's disease, Zambian adults