Parkinson's disease (PD) is the second most frequent neurodegenerative disorder after Alzheimer's disease. It causes motor dysfunctions, such as bradykinesia, resting tremor, rigidity and postural instability. Although PD appears to be sporadic in most cases, several causative genes and susceptibility factors have been identified that cause familial forms of the disease with Mendelian inheritance with autosomal dominant or autosomal recessive inheritance.
Approximately 5~10% of patients with the clinical picture of PD carry a mutation in one of the known genes that cause monogenic forms of the disorder. The average age at onset is between 60 and 80 years and the average age of diagnosis is 60 years. Onset of primary parkinsonism before 50 years is known as early onset parkinsonism(EOP). Onset between 20 and 50 years is known as young-onset PD. Onset at younger than 20 years is known as juvenile parkinsonism (JP). At least, 13 loci and 9 genes are reported. The investigators study is aimed to screen the clinical diagnosed familial EOP for the common mutation site by PCR/DNA sequencing. The gene for screen are Parkin (pattern: PARK2), PINK1 (pattern: PARK6) and ATP13A2 (pattern: PARK9).