The genetic defect dentatorubral-pallidoluysian atrophy (DRPLA) is caused by expansion of a CAG trinucleotide repeat. The mutant gene is translated into protein whose electrophoretic mobility correlates to the number of expanded CAG trinucleotide repeats, indicating that the protein carries an expanded glutamine repeat. Using two polyclonal antibodies raised against the DRPLA gene product in immunoblotting, we determined the untruncated DRPLA proteins, and showed that the amounts of mutant and wild-type DRPLA proteins were similar in DRPLA brain tissues and lymphoblastoid cells, suggesting that regulation of the level of translation of the DRPLA gene is not central to the development of the disease.