The lack of CLOCK oscillatory expression, as well as the lack of its acetylation activity, can result in altered amplitude and/or acrophase of BMAL1/CLOCK heterodimer target genes belonging to the basic loop (PER1–3, CRY1–2) or to the auxiliary loop (NR1D1), as displayed in PD fibroblasts. The gene discussed is CRY1; the disease is Parkinson disease.