GM2A and Parkinson disease: A subsequent colocalization analysis (PPH4 > 0.8) confirmed that, of the 12 proteins linked to cognitive progression, 10 (ALKBH3, GLO1, IDO1, SERPINA3, SORD, TPST1, GM2A, MICB, SH3BGRL3, and TGFBI) shared causal variants with PD cognitive progression loci (Table S6, Figure 3).