The genetic background of PD encompasses a complex interplay of monogenic and polygenic risk factors, gene-environment interactions, and modifiers of disease penetrance and expressivity, which all contribute to disease susceptibility. While the majority of PD cases are sporadic (without a known genetic cause), a small percentage of cases are considered familial, meaning they have a genetic component. Understanding the genetic basis of PD is essential for elucidating disease mechanisms, identifying novel therapeutic targets, and developing personalized treatment approaches for affected individuals.