SNCAIP

The SNCAIP gene provides instructions for making a protein called synphilin-1 and a slightly different version of this protein called synphilin-1A. These proteins are produced in the brain. They are usually located in specialized structures called presynaptic terminals, found at the tips of nerve cells. In nerve cells, synphilin-1 and synphilin-1A interact with another protein called alpha-synuclein. The functions of synphilin-1 and synphilin-1A, however, are unknown.

Parkinson disease - associated with the SNCAIP gene

One SNCAIP mutation has been identified in a small number of people with Parkinson disease. This mutation leads to a change in one of the building blocks (amino acids) used to make synphilin-1. Specifically, the amino acid arginine is replaced by the amino acid cysteine at position 621 in the protein's chain of amino acids (written as Arg621Cys or R621C).

Because the Arg621Cys mutation has been reported in so few cases, it is unclear whether the mutation affects the risk of Parkinson disease. Some studies indicate that altered synphilin-1 proteins cluster together (aggregate), which could disturb normal cell activities and lead to the death of nerve cells.

Synphilin-1 and alpha-synuclein are components of Lewy bodies, protein deposits that appear in brain cells of people with certain diseases of the nervous system. Lewy bodies in a region of the brain called the substantia nigra, which controls balance and movement, are a characteristic feature of Parkinson disease.