The latest research once again confirmed that specific HLA-DRB1 variants are associated with a reduced risk of PD and suggested that this protective effect is primarily caused by specific amino acid polymorphisms present in most HLA-DRB1*04 subtypes (Naito et al., 2021; Yu et al., 2021; Le Guen et al., 2023). The gene discussed is HLA-DRB1; the disease is Parkinson disease.