BMP4 and Parkinson disease: For example, genetic studies have found ESR1 gene polymorphisms may be linked to PD susceptibility (Handel et al., 2013), IGF1R was discovered to have anti-inflammatory properties in a rat model of PD (Xu et al., 2009; Du et al., 2021), BMP4 can induce the phenotypic of striatal dopaminergic neurons in vitro (Stull et al., 2001).