POLG and Parkinson disease: POLG1 mRNA levels from six PD patients' peripheral blood lymphocytes with the main G/G+T/T genotype of haplotype1 in intron 11 had 1.7 fold (95%CI: 1.1–2.8) higher levels than A/A+A/A carriers combined (P = 0.003 in PD patients and P = 0.004 in healthy controls), with no interactions between genotypes and sex (Figure 5A).