BACKGROUND: Mutations in parkin have been associated with autosomal recessive 
early-onset Parkinson's disease (PD). Here, we report on unusual phenotypic 
variability within a family with mutations in parkin.
METHODS: The proband and her parents were clinically assessed. Mutation analysis 
was performed using genomic DNA and complementary DNA. The protein expression of 
Parkin and Mitofusin 2 was examined by western blotting.
RESULTS: The proband was a compound heterozygote with no detectable Parkin and 
presented with early-onset PD. The father, a single heterozygote with reduced 
expression of Parkin, had mild loss of arm swing. The mother, who had only very 
mild rigidity, was unexpectedly found to be a homozygote with no Parkin 
expression. The proband, but not the parents, met the Queen Square Brain Bank 
criteria for PD. Parkin-dependent ubiquitination of Mitofusin 2 was impaired in 
the mother and the proband.
CONCLUSION: We report the first case of a homozygous mutation carrier in parkin 
who had no functional protein and only mild signs of parkinsonism in her seventh 
decade, whereas her daughter developed typical early-onset PD. This family 
demonstrates phenotypic variability in parkin-related parkinsonism. © 2012 
Movement Disorder Society.