Objective: To describe a large consanguineous family in which inheritance of a 438- to 477-base pair deletion in exon 3 (Ex3Delta40) in the parkin gene resulted in parkinsonism (age range at onset, 24-32 years).
Design: Fifty-two family members underwent genetic analysis.
Main outcome measure: Two clinical examiners blinded to genetic status evaluated 21 family members, including all mutation carriers (4 homozygous and 12 heterozygous individuals; 5 family members did not have the mutation).
Results: In this family, the parkin Ex3Delta40 mutation is recessive; only homozygotes manifest symptoms of early-onset levodopa-responsive parkinsonism, including resting tremor, dystonia, and slow progression, with the caveat that presymptomatic signs of dopaminergic loss in heterozygotes must be excluded by fluorodopa F 18 with positron emission tomography. This contrasts with the autosomal dominant pattern of inheritance of parkinsonism described in families with the same mutation.
Conclusion: In families with a dominant inheritance, an additional genetic or environmental cause must coexist with the Ex3Delta40 mutation.