CERS4 and Parkinson disease: In contrast, significantly increased expression levels of KDSR (log2FC 0.56; 95% CI 0.30–0.82, P < 0.001; Fig. 4F), SPTLC2 (log2FC 0.31; 95% CI 0.07–0.55, P = 0.012; Fig. 4G), SPTLC3 (log2FC 0.31; 95% CI 0.04–0.58, P = 0.027; Fig. 4H), SPTSSA (log2FC 0.27; 95% CI 0.00–0.54, P = 0.049; Fig. 4I), CERS2 (log2FC 0.35; 95% CI 0.00–0.70, P = 0.047; Fig. 4J), and CERS4 (log2FC 0.37; 95% CI 0.05–0.68, P = 0.021; Fig. 4K) were observed in SN samples of PD patients.