Parkinson's disease

In medicine, Parkinson disease (PD), also called primary Parkinsonism, Paralysis Agitans, and other names, is a disease affecting movement. "The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination". In other words, Parkinson's disease is a Parkinsonian disorders, but not all Parkinsonian disorders are true Parkinson's disease.

Formally, it is progressive, degenerative neurologic disease characterized by a tremor that is maximal at rest, retropulsion (i.e. a tendency to fall backwards), rigidity, stooped posture, slowness of voluntary movements, and a masklike facial expression. Pathologic features include loss of melanin containing neurons in the substantia nigra and other pigmented nuclei of the brainstem. Lewy bodies are present in the substantia nigra and locus coeruleus but may also be found the related diffuse Lewy body disease characterized by dementia in combination with varying degrees of parkinsonism. (Adams et al., Principles of Neurology, 6th ed, p1059, pp1067-75) More specifically, via genes such as leucine-rich repeat kinase 2 (LRRK2).