Objective To explore the effects of a variable polyglutamine repeat on the ATXN1 gene transcription. Methods Wild-type ATXN1 (29Q) and mutant ATXN1 (61Q) genes were constructed by molecular cloning. The expression vectors were generated by inserting wild-type and mutant ATXN1 genes into the pLVX-Puro-3xflag-C vector. Lentiviruses were generated by infecting the expression vectors into human embryonic kidney 293T cells. The expression levels of wild-type and mutant ATXN1 mRNA in 293T cells were detected by a real-time RT-polymerase chain reaction. Results The relative levels were (661.9?±?17.7) and (381.0?±?20.5) for wild-type and mutant ATXN1 mRNA in 293T cells, respectively. The relative level of wild-type ATXN1 mRNA was higher than that of mutant ATXN1 mRNA (P?