Interleukin 6 (IL6) is increased in serum from biallelic PRKN/PINK1 mutation carriers compared to healthy controls. IL6 levels in serum samples from Parkinson’s disease (PD) patients with mutations in PRKN/PINK1, unaffected mutation carriers, idiopathic Parkinson’s disease (IPD) patients, and healthy control subjects (HC). (A) Patients with Parkinson’s disease due to biallelic PRKN/PINK1 mutations (mut+/+ PD+, n = 15) exhibited higher IL6 levels compared to healthy controls (n = 84). Unaffected heterozygous mutation carriers (mut+/− PD−, n = 13) showed similar IL6 levels compared to affected heterozygous mutation carriers (mut+/− PD+, n = 18). (B) Investigating an independent cohort from Italy yielded similar group differences as presented in A, while the total amount of IL6 among all participants was lower compared to the German cohort due to a batch effect (mut+/+ PD+, n = 19; mut+/− PD+, n = 5; mut+/− PD−, n = 9; HC, n = 9). Regarding the Italian cohort, biallelic PRKN/PINK1 mutation carriers exhibited increased IL6 levels compared to unaffected heterozygotes. Moreover, there was a trend towards elevated IL6 levels in PRKN/PINK1 affected heterozygotes compared to healthy control subjects. (C) In the German cohort, PRKN/PINK1 biallelic patients showed a trend towards higher IL6 levels compared to patients with idiopathic Parkinson’s disease (n = 51), while idiopathic Parkinson’s disease patients exhibited a trend towards elevated IL6 release compared to healthy control subjects. As multiple testing was performed, the significance level was adjusted to α = 0.0167. The assumed order among the different groups was tested with the Jonckheere-Terpstra test (bold, lower left corner). Pairwise differences between two groups were assessed using the Wilcoxon rank sum test. Data are presented as box and whisker plots. The box extends from the 25th to the 75th percentile. The line in the middle of the box represents the median. Tukey whiskers are used.