title: Phase analysis identifies compound heterozygous deletions of the PARK2 gene in patients with early-onset Parkinson disease.
abstract: Exon rearrangements and point mutations are common in PARK2, the most important causative gene of autosomal recessive early-onset Parkinson disease (EOPD). However, gene dosage analysis alone cannot conclusively determine the phase of exon rearrangements and the incidence of molecularly confirmed parkin-type EOPD may be underestimated. To fully characterize the mutation spectrum, we performed sequencing and gene dosage analyses of SNCA, PARK2, PINK1, and PARK7 in 114 unrelated EOPD patients with onset age ≤40 years. Mutational phase of exon rearrangements was determined by reverse-transcriptase PCR (RT-PCR) and sequence analysis using a patient's own RNA. Fourteen different PARK2 mutations (3 point mutations plus 11 exon rearrangements) were identified in 18 patients, comprising 1 homozygote (0.9%), 13 compound heterozygotes (11.4%), 3 single heterozygotes (2.6%), and 1 with unknown phase (0.9%). By phase determination, more than 80% (5 of 6) of patients with apparently contiguous multi-exon deletions and 30% (5 of 18) of all PARK2 mutation carriers were additionally diagnosed as compound heterozygotes, respectively. This study shows that compound heterozygous mutations constituted a significant portion of patients with apparently contiguous multi-exon deletions. Phase determination is a prerequisite to molecular diagnosis for autosomal recessive EOPD, especially in subjects with PARK2 exon rearrangements.
authors.affiliation: Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: S Y
authors.initials: SY
authors.lastname: Kim
authors.forename: M W
authors.initials: MW
authors.lastname: Seong
authors.forename: B S
authors.initials: BS
authors.lastname: Jeon
authors.forename: S Y
authors.initials: SY
authors.lastname: Kim
authors.forename: H S
authors.initials: HS
authors.lastname: Ko
authors.forename: J Y
authors.initials: JY
authors.lastname: Kim
authors.forename: S S
authors.initials: SS
authors.lastname: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D044466:Asian People; D001483:Base Sequence; D002648:Child; D005091:Exons; D005260:Female; D018628:Gene Dosage; D006579:Heterozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010300:Parkinson Disease / Q000235:genetics*; D020734:Parkinsonian Disorders; D017354:Point Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D044767:Ubiquitin-Protein Ligases / Q000235:genetics*
chemical_list: D044767:Ubiquitin-Protein Ligases; C111567:parkin protein