Many studies suggests an involvement of PRG-1 in the pathogenesis and/or reparation attempts in neurological disease such as epilepsy 34, 38, 39, neurotrauma, Parkinson's disease 36, memory impairment 35 and cancer, including tumor progression or metastasis because of its putative target of LPA, a pro-cancerogenous factor 46, 80. Here, PLPPR4 is linked to Parkinson disease.