Modified somatosensory processing in PINK1 (PARK6)-mutation carriers: preclinical evidence by the use of quantitative sensory testing

Introduction: Sensory symptoms are common in Parkinson's disease (PD). It is unclear whether these symptoms are of primary origin or secondary due to pathophysiological changes occurring in PD. Recently, mutations of the PINK1 (PARK6) gene have been identified as one cause for the development of PD. Asymptomatic carriers of PINK1 mutations represent individuals at risk who can be identified prior to the development of PD by molecular genetic testing. Therefore, PINK1-associated PD may serve as a model to detect presymptomatic signs and sensory abnormalities before subjects show definite clinical signs of PD. This might shed light on the pathomechanisms related to sensory abnormalities in patients with the more frequent idiopathic PD. Methods: 14 family-members with PINK1 mutation (3 homozygous, 11 heterozygous) and 14 healthy controls were examined. A clinical examination, nerve conduction studies and a shortened form of the QST protocol of the German Research Network on Neuropathic Pain (DFNS) were performed. The QST protocol included perception thresholds for warm, cold, cold pain, heat pain, mechanical and painful mechanical stimuli, vibration and pain pressure. For evaluation, z-values were calculated and compared by the U-test. P