Genes And Parkinsonism

Parkinsonism is a syndrome of rest tremor, rigidity, bradykinesia, loss of postural reflexes, and the freezing phenomenon.1-1-1 Most often, it is a manifestation of Parkinson's disease (PD), which is characterized neuro-pathologically by brainstem Lewy bodies. Recent epide-miological and molecular data suggest that this is not one disorder, but is comprised of at least several disorders with genetic, environmental, or mixed etiologies. Genes play a complex role in PD. Most twin studies, which are powerful tools in dissecting genetic from environmental contributions to the disease, have discounted a genetic influence in PD. However, it is difficult to draw solid conclusions from them because of methodological short-comings.[2] The largest of them, an unselected population-based cross-sectional twin study, has shown similar concordance for PD in monozygotic (MZ) and dizygotic (DZ) twin pairs with onset >50 years, but a striking concordance in MZ pairs with onset <50 years.[3] This is consistent with a strong genetic component in young-onset disease. This does not support a strong genetic component in late-onset disease, but a large population-based and geneological study in Iceland[4] showed that 560 patients with late-onset PD were significantly more related to each other than were subjects in matched groups of controls. The risk ratio (RR) for PD was 6.7 [95% confidence interval (CI), 4.3-9.6] for siblings, 3.2 (95% CI, 1.2-7.8) for offspring, and 2.7 (95% CI, 1.6-3.9) for nephews and nieces of patients with late-onset PD. The study claimed that shared environmental influences in late-onset PD are not the explanation because the relatedness extended beyond the nuclear family and spouses was not at increased risk. However, the different RR values for siblings and offspring are consistent with shared environmental factors in early life. [18F] dopa positron emission tomography (PET) studies in MZ and DZ twin pairs discordant for PD[5] showed reduced striatal uptake not only in the affected twin but also in the clinically unaffected twin, indicating that concordance for nigral pathology in twins with PD is higher than that suggested by clinical twin studies.

Most familial aggregation studies indicate a familial component in PD, but have not adequately compared early-onset vs. late-onset disease.[6] A recent community-based study, in which 221 probands had onset <50 years and 266 had onset >50 years, found significantly greater risk in siblings (RR of 7.9; 95% CI, 2.5-25.5), but not parents (RR of 1.7; 95% CI, 0.9-3.3), of early-onset cases; however, the RR in parents and siblings of late-onset cases was similar (roughly 2-3), confirming a familial component in both early-onset and late-onset PD and further suggesting a recessive genetic influence in early-onset disease.[6]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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