Changes in catalase expression have been linked to various diseases, including neurological disorders such as AD and PD [67], psychiatric conditions such as bipolar disorders and schizophrenia [68], cardiovascular issues, such as hypertension [69], metabolic disorders, including diabetes [70], autoimmune diseases, such as vitiligo [71], Wilson’s disease [72], and cancer [64]. The gene discussed is CAT; the disease is Parkinson disease.