PArkin Co-Regulated Gene (PACRG) is a novel gene which is transcriptionally co-regulated with the parkin gene (PRKN) by a shared bi-directional promoter. To determine whether mutations in PACRG are associated with early-onset Parkinson's disease (EO-PD), we performed sequence and dosage analysis of 76 EO-PD patients from a Taiwanese-Ethnic Chinese cohort. This analysis identified two novel nucleotide variants in the non-coding region of PACRG. One patient had an IVS2+247851T>C heterozygous change and two patients had an IVS4+78A>G heterozygous alteration. Neither of these variants was present in the 91 controls tested. A third intronic polymorphism (IVS1+85744insC) was present in cases and controls at an equivalent frequency (approximately 0.25). To facilitate gene dosage analysis, we identified cell lines with a heterozygous deletion or duplication of the entire PACRG locus. Three patients with heterozygous dosage alterations were identified, including two patients with an exon 2 duplication and one patient with an exon 3 deletion of PACRG. No dosage alterations were observed in the 91 controls analyzed (chi(2)=3.66, P=0.056). Our results suggest that point mutations in PACRG are not a common cause of EO-PD but haploinsufficiency for PACRG may be associated with disease.