Early-onset familial parkinsonism due to POLG mutations.
OBJECTIVE
To define the molecular etiology of early-onset parkinsonism and peripheral neuropathy.


METHODS
Two sisters had early-onset parkinsonism (dystonic toe curling, action tremor, masked face, bradykinesia, stooped posture, and rigidity), together with clinical and electrophysiological signs of sensorimotor axonal peripheral neuropathy.


RESULTS
No mutations were found in the genes for parkin or PINK1. Muscle biopsies showed ragged-red and cytochrome c oxidase-negative fibers, and biochemistry showed decreased activities of respiratory chain complexes containing mitochondrial DNA-encoded subunits. Multiple mitochondrial DNA deletions were seen by long polymerase chain reaction, and sequencing of the POLG gene showed that the patients were compound heterozygous for two patogenic mutations.


CONCLUSIONS
POLG mutations can cause early-onset parkinsonism in the absence of progressive external ophthalmoplegia.
Davidzon
Guido
G
Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA.
Greene
Paul
P
Mancuso
Michelangelo
M
Klos
Kevin J
KJ
Ahlskog
J Eric
JE
Hirano
Michio
M
DiMauro
Salvatore
S
D000328:Adult; D017668:Age of Onset; D000595:Amino Acid Sequence; D004247:DNA / Q000235:genetics; D000074002:DNA Polymerase gamma; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004421:Dystonia / Q000503:physiopathology; D005260:Female; D005808:Genes, Recessive / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000473:pathology; D009154:Mutation; D009468:Neuromuscular Diseases / Q000503:physiopathology; D017246:Ophthalmoplegia, Chronic Progressive External / Q000473:pathology; D010300:Parkinson Disease / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D014202:Tremor / Q000503:physiopathology
D004272:DNA, Mitochondrial; D004247:DNA; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase