The ATN1 gene provides instructions for making a protein called atrophin 1. Although the exact function of this protein is unknown, it appears to play an important role in nerve cells (neurons) in many areas of the brain. Based on studies in other animals, researchers speculate that atrophin 1 may act as a transcriptional co-repressor. A transcriptional co-repressor is a protein that interacts with other DNA-binding proteins to suppress the activity of certain genes, although it cannot attach (bind) to DNA by itself.
One region of the ATN1 gene contains a particular DNA segment known as a CAG trinucleotide repeat. This segment is made up of a series of three DNA building blocks (cytosine, adenine, and guanine) that appear multiple times in a row. In most people, the number of CAG repeats in the ATN1 gene ranges from 6 to 35.
Dentatorubral-pallidoluysian atrophy (DRPLA) results from an increased number of copies (expansion) of the CAG trinucleotide repeat in the ATN1 gene. In people with this condition, the CAG segment is abnormally repeated at least 48 times, and the repeat region may be two or three times its usual length. Although the extended CAG region changes the structure of atrophin 1, it is unclear how the altered protein damages brain cells. Researchers believe that abnormal atrophin 1 accumulates in neurons and interferes with normal cell functions. The dysfunction and eventual death of neurons in many parts of the brain lead to involuntary movements, intellectual decline, and the other characteristic features of DRPLA.
- dentatorubral-pallidoluysian atrophy protein