The phenotype of the A30P mutation in the SNCA gene is similar to that of sporadic IPD, including a high variability of the age at disease onset, ranging from 54 to 76 years. The follow-up of presymptomatic carriers of the A30P mutation may give insight into preclinical disease stages and early manifestations of PD.

Increased echogenicity of the SN, characteristically seen in Parkinson disease, is related to a functional impairment of the nigrostriatal system (even in young healthy adults) that can be revealed by [18F]-dopa PET studies. Substantia nigra hyperechogenicity is related to a higher tissue iron level, which is known to enhance the cells' generation of reactive oxygen specimens. Therefore, we hypothesize that transcranial sonography may identify a susceptibility marker for the development of nigral injury that can be detected early in life, prior to the onset of Parkinson disease.

No abstract