Another Parkinsons trigger gene found. It's responsible for housekeeping of protein junk.

Dr. Ferrer, UBC.

A spelling mistake in gene EIF4G1 triggers Parkinson's.    50% of one French family had the disease and study by a UBC group identified this gene and its role. When cells are stressed, the gene normally makes a protein which helps recycle cell waste. This can explain "Lewy bodies" which are collections of discarded protein that remain trapped in certain brain cells.

Eight other genes can contribute.

Added:  Loss of dopamine in a small group of brain cells that time movement triggers Parkinsons symptoms in mice.  There are two types of "medium spiny neurons" (MSN) that act as "gas pedal and brake" which are fed by "fast spiking neurons" (FSN).  When dopamine is depleted, FSN nerves begin to rewire and preferentially supply signals to one type of MSN with tremors following.