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Parkinsonism Relat Disord. 2017 Sep;42:95-99. doi: 10.1016/j.parkreldis.2017.07.003. Epub 2017 Jul 8.

Influence of L-dopa on subtle motor signs in heterozygous Parkin- and PINK1 mutation carriers.

Author information

1
Institute of Neurogenetics, University of Luebeck, Germany; Department of Neurology, University of Luebeck, Germany.
2
Institute of Medical Biometry and Statistics, University of Luebeck, Germany.
3
Institute of Neurogenetics, University of Luebeck, Germany; Department of Psychiatry and Psychotherapy, University of Luebeck, Germany.
4
Center for Biomedicine, European Academy of Bolzano, Bolzano, Italy.
5
Institute of Neurogenetics, University of Luebeck, Germany.
6
Institute of Neurogenetics, University of Luebeck, Germany. Electronic address: christine.klein@neuro.uni-luebeck.de.

Abstract

INTRODUCTION:

A latent nigrostriatal deficit and its possible clinical consequences in asymptomatic heterozygous Parkin and PINK1 mutation carriers (AMC) have been a matter of investigation in recent years. Notably, mild Parkinsonian signs in heterozygous mutation carriers can be so subtle that they may be missed if not specifically investigated.

METHODS:

We studied 15 heterozygous Parkin and PINK1 AMC and 18 age- and sex-matched mutation-negative controls using a standardized video, instructing the probands to perform relevant parts of the UPDRS III to investigate fine motor movements at baseline and after first-time L-Dopa administration. Additionally, available UPDRS III scores of mutation carriers from the past ten years were reviewed.

RESULTS:

AMC showed a reduced number of fine motor movements per second compared to controls at baseline (p = 0.04). L-Dopa improved motor performance numerically but non-significantly in AMC (p = 0.2301), but significantly in healthy controls (p = 6.1·10-5). Although none of the AMC reported symptoms, nine showed rigidity, bradykinesia, tremor, and postural instability when the UPDRS III was applied. Mean UPDRSIII scores significantly decreased after L-Dopa administration (p = 0.005), but did not increase over the past ten years.

CONCLUSIONS:

(i) Heterozygous AMC show subtle motor abnormalities when a detailed, specialized motor examination is applied and compared to mutation-negative matched control subjects. (ii) The mild motor deficit present in a subgroup of heterozygous Parkin and PINK1 AMC appears to be non-progressive and responsive to L-dopa administration. (iii) Evaluating motor changes, their progression, and treatment response in AMC can provide valuable insights into possible early disease stages and compensatory mechanisms.

KEYWORDS:

Genetics; Heterozygous; Parkinsonism; Rating scales

[Indexed for MEDLINE]

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