The invention concerns methods for diagnosis or prognosis of Parkinson's disease in a subject. Said method comprises steps which consist in detecting the presence or the absence of the CYP2D6-B homozygotic mutation and the GSTM1 homozygotic deletion. The joint presence of the CYP2D6-B homozygotic mutation and the GSTM1 homozygotic deletion indicates that the subject may be suffering from Parkinson's disease or shows an increased risk of developing Parkinson's disease.
