Genetic mutations play a pivotal role in the development of diseases like cancer and Alzheimer’s by altering normal cellular functions. In cancer, mutations can occur in genes that regulate cell growth, division, and apoptosis, leading to uncontrolled cell proliferation. Oncogenes, when mutated, become overactive and promote tumor growth, while tumor suppressor genes lose their ability to control cell division and repair DNA damage. For instance, mutations in the TP53 gene, which encodes the p53 protein, impair its function as a tumor suppressor, leading to unchecked cellular growth and cancer progression.

In Alzheimer’s disease, genetic mutations can disrupt neuronal function and promote the accumulation of toxic proteins. Mutations in the APP, PSEN1, and PSEN2 genes are associated with early-onset Alzheimer’s. These mutations result in the abnormal processing of amyloid precursor protein (APP), leading to the accumulation of amyloid-beta plaques, a hallmark of Alzheimer’s pathology. Additionally, mutations in the APOE gene, particularly the APOE ε4 allele, increase the risk of late-onset Alzheimer’s by influencing amyloid-beta deposition and clearance, as well as lipid metabolism and neuronal repair.

These genetic alterations, through their impact on cellular pathways, contribute significantly to the onset and progression of complex diseases like cancer and Alzheimer’s.