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Abstract
Objective: To ascertain in a cross-sectional study whether substantia nigra (SN) echogenicity, olfaction, and dopamine transporter (DaT)-SPECT are reliable premotor biomarkers in a cohort of asymptomatic carriers of the LRRK2 G2019S mutation (AsG2019S+).
Methods: These biomarkers were evaluated in 49 AsG2019S+ patients, and we also studied olfaction and SN echogenicity in 29 patients with G2019S-associated Parkinson disease (PD-G2019S), 47 relatives who were noncarriers of the LRRK2 G2019S mutation (AsG2019S−), 50 patients with idiopathic Parkinson disease (iPD), and 50 community controls.
Results: Eighty-five percent of unaffected mutation carriers (AsG2019S+) showed pathologic SN hyperechogenicity, with a similar proportion observed among both PD-G2019S and iPD cases, and 41% of AsG2019S− also showing increased SN echogenicity. The proportion of hyposmic individuals was not statistically different in patients with PD-G2019S (50%) and iPD (82%), but hyposmia was significantly less common in both AsG2019S+ (26%) and AsG2019S− (28%). In AsG2019S+ cases, reduced striatal uptake in DaT-SPECT was observed in 43.7%.
Conclusions: Independently of age at examination, the most frequently altered premotor biomarker in LRRK2 G2019S-associated PD was SN hyperechogenicity, whereas abnormal DaT-SPECT predominated in older, unaffected mutation carriers.
GLOSSARY
- AsG2019S−=
- asymptomatic G2019S mutation noncarriers;
- AsG2019S+=
- asymptomatic G2019S mutation carriers;
- aSNmax=
- mean maximal area of increased echogenicity in the substantia nigra;
- DaT=
- dopamine transporter;
- iPD=
- idiopathic Parkinson disease;
- PD=
- Parkinson disease;
- PD-G2019S=
- patients with Parkinson disease carrying the G2019S mutation;
- ROC=
- receiver operating characteristic;
- SN=
- substantia nigra;
- TCS=
- transcranial sonography;
- UPSIT=
- University of Pennsylvania Smell Identification Test
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Editorial, page 608
- Received June 5, 2012.
- Accepted September 21, 2012.
- © 2013 American Academy of Neurology
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