Final answer:
Loss of dopamine neurons in the substantia nigra results in Parkinson's disease, a neurodegenerative disorder characterized by symptoms such as tremors, rigidity, slowness of movement, and postural instability.
Step-by-step explanation:
Loss of dopamine neurons in the substantia nigra results in Parkinson's disease. Parkinson's disease is a neurodegenerative disorder characterized by the progressive death of neurons in the midbrain. This leads to symptoms such as tremors, rigidity, slowness of movement, and postural instability.