PDE9A and Parkinson disease: To assess differences in gene expression between SCA7 and WT PCs, we employed qRT-PCR to measure the expression levels of Aldoc, Fam107b, Ipo5, and Calb1 alongside several phosphodiesterases (PDEs), namely Pde1c, Pde4d, Pde9a, and Pde10a. PDEs were chosen for screening due to their pivotal role in the cyclic nucleotide signaling pathway, which has been observed to deteriorate in aging brains17,18 and in Alzheimer disease (AD),19,20 Parkinson disease (PD),21 and Huntington disease (HD).22