phenotype can be
Abstract—Mutations in the PINK1 gene cause autosomal recessive parkin-
sonism characterized by early onset and a variable phenotypic presentation. A
patient homozygous for the Ala168Pro mutation has been fully characterized
clinically. Apart from onset at age 39 years and the excellent and sustained
response to levodopa, all clinical and laboratory features, including SPECT and
assessment of autonomic function, were indistinguishable from typical idio-
pathic Parkinson disease.
A. Albanese, MD; E.M. Valente, MD, PhD; L.M. Romito, MD; E. Bellacchio, PhD; A.E. Elia, MD;
and B. Dallapiccola, MD
The phenotypic core of Parkinson disease (PD) (rest-
ing tremor, rigidity, bradykinesia, and postural in-
stability) is often associated with other signs, such as
sleep disturbances, depression, and mild autonomic
dysfunction. Autosomal recessive early-onset parkin-
sonism (EOP) can be indistinguishable from spo-
radic, late-onset idiopathic PD, yet patients often
show atypical features such as dystonia at onset,
hyperreflexia, sleep benefit, early occurrence of
levodopa-induced dyskinesias, and behavioral or psy-
chiatric abnormalities. Mutations in the PINK1
gene, encoding a putative serine-threonine kinase
with likely mitochondrial localization, have recently
been identified as responsible for familial and spo-
radic EOP,1-5but the spectrum of PINK1-associated
phenotypes needs further definition. In most Italian
patients, the phenotype closely resembles typical id-
iopathic PD, with unilateral onset and absence of
atypical signs, the only distinguishing feature being
a more benign course.1,2We report here a detailed
clinical and laboratory analysis of the sporadic Ital-
Ala168Pro mutation, including SPECT and assess-
ment of autonomic and mitochondrial functions.
born in central Italy. He denied parental consanguinity, albeit
both parents had the same family name.
Parkinsonian signs started at age 39 years, with gait impair-
ment due to akinesia of the right leg. A year later, he noticed
motor impairment of the right upper limb and started levodopa
treatment (50 mg QID), with immediate improvement. After 6
This patient is a 54-year-old carpenter who was
years, the patient consulted us complaining of freezing of gait.
Pergolide (1 mg TID) was added with sustained benefit, and the
patient remained in this combination therapy until now.
Upon observation after 15 years from onset, the patient had a
typical parkinsonian picture with right-side prevalence and re-
ported excellent response to treatment. Characteristic features of
EOP, such as dystonia at onset, early or severe levodopa-induced
dyskinesias, sleep benefit, and hyperreflexia, were absent. He had
facial hypomimia, mild akinesia in the upper limbs, and mild “on”
period right-foot dystonia. Mood was normal with no behavioral
abnormalities. The patient was in excellent motor condition; in his
best “on” state (after the first morning dose of treatment) the
Unified Parkinson’s Disease Rating Scale (UPDRS) motor score
was 12 (see video E-1 on the Neurology Web site at www.neurology.
org). He could appreciate the wearing-off of the first morning dose.
“Off” period motor fluctuations occurred occasionally in the afternoon
as festination without freezing. He had mild urinary urgency but
reported no other autonomic dysfunction; drug intake was not asso-
ciated with hypotension.
To assess the motor condition in the “off” state, antiparkinso-
nian medication was withdrawn. The patient’s motor condition
gradually worsened and mood became depressed. On the fifth day,
he had a UPDRS motor score of 49 that decreased to 12 after a
single challenge of 200/50 mg levodopa/benserazide. During drug
withdrawal, there was no dysautonomia and urinary complaints
did not change; on examination, he had a moderate impairment of
speech and facial hypomimia, significant akinesia and rigidity in
all four limbs, and a severe disturbance of gait with festination,
freezing, and postural instability (see video E-2).
A complete neuropsychological profile was obtained by admin-
istering a battery for global mental status examination, in addi-
tion to specific tests for memory, executive functions, verbal
fluency, and comprehension. All test results were normal. A psy-
chiatric interview was unremarkable and the Neuropsychiatric
Inventory was normal.
SPECT after administration of methyl-3-?-(4-?[123I]iodo-
phenyl)tropane-2?-carboxylate ([123I]?-CIT) was performed to vi-
sualize the nigrostriatal projections in three regions of interest
(ROI) for each hemisphere, corresponding to the anterior puta-
men, the posterior putamen, and the caudate nucleus. Striatal
[123I]?-CIT uptake was severely decreased on both sides in a sim-
ilar manner. Compared with occipital background activity, dopa-
minergic denervation was more severe in the putamen (ratio: 1.5
on each side) than in the caudate nucleus (ratio: 2.5 on the right,
2.9 on the left).
Mitochondrial function was assessed by dosing the respiratory
chain enzymatic activity, citric acid cycle, and electron transport
rate on a biopsy sample of the left quadriceps muscle. At rest,
blood lactate was slightly elevated (1906 ?mol/L; normal 500 to
1800), whereas pyruvate was within normal limits. No other ab-
normality of mitochondrial function was detected. EMG and nerve
conduction study results were normal. Muscle morphology and
histochemistry revealed normal tissue organization and distribu-
tion of the oxidative enzymes activity. Degeneration, ragged red
fibers, and pathologic accumulation of lipids or carbohydrates
were not observed.
Assessment of autonomic function showed a mild impairment
of sympathetic nervous system function. Systolic blood pressure
dropped to borderline normal values (up to 20 mm Hg after 7
Additional material related to this article can be found on the Neurology
Web site. Go to www.neurology.org and scroll down the Table of Con-
tents for the June 14 issue to find the link for this article.
From the National Neurologic Institute ‘‘Carlo Besta’’ and Universita ` Cat-
tolica del Sacro Cuore (Drs. Albanese, Romito, and Elia), Milan, IRCCS CSS
(Drs. Valente, Bellacchio and Dallapiccola), Mendel Institute, Rome; and
Department of Experimental Medicine and Pathology (Dr. Dallapiccola), La
Sapienza University, Rome, Italy.
Supported by Telethon grant no. GGP04291 and by the Italian Ministry of
Health (Ricerca Finalizzata 2003).
Received January 21, 2005. Accepted in final form March 1, 2005.
Address correspondence and reprint requests to Dr. Alberto Albanese, Isti-
tuto Nazionale Neurologico Carlo Besta, Via G. Celoria, 11, 20133 Milan,
Italy; e-mail: firstname.lastname@example.org
Copyright © 2005 by AAN Enterprises, Inc.
minutes) during the head-up tilt to 60 degrees. Heart rate in-
crease compensated adequately. The Valsalva maneuver was al-
tered: There was no blood pressure overshoot and postmaneuver
bradycardia was detected, indicating an initial sympathetic vaso-
constrictor failure. An abnormality of the sympathetic efferent
pathways was confirmed by the lack of reflex blood pressure in-
crease on the skin cold test, whereas the Valsalva ratio was nor-
mal, indicating preserved parasympathetic function.
Sympathetic innervation to the heart was evaluated with car-
diac scintigraphy using radiolabeled
guanidine ([123I]MIBG). Global [123I]MIBG uptake was assessed
by measuring the ratio of [123I]MIBG uptake in the left heart
ventricle compared with that in the upper mediastinum on planar
scintigraphic data. In the laterobasal and inferior walls of the left
ventricle, there was a 1.71 ratio indicating partial ?-adrenergic
denervation (normal values 2.2 ? 0.2) (figure 1).
diagnosis of typical PD with early onset. After 15
years of disease duration, the phenotype had slowly
progressed without the appearance of atypical fea-
tures. Clinical and laboratory examination results
The patient reported here received a
were in keeping with the findings commonly ob-
served in idiopathic PD, including dopaminergic de-
nervation, mild dysautonomia, and absence of
cognitive or psychiatric disturbances. Unlike an ear-
lier report of fluorodeoxyglucose-DOPA PET scans in
PINK1 familial cases,6the striatal dopaminergic de-
nervation observed with [123I]?-CIT SPECT was sim-
ilar to that reported in late-onset PD.7
There is increasing evidence that impairment of
mitochondrial function and oxidative damage are
contributing factors for PD, and all EOP genes seem
to be involved in mitochondrial activity.8Yet muscle
mitochondrial function in this patient was normal,
indicating that the putative influence of PINK1 de-
fect on brain mitochondrial function is not detectable
in the periphery, at least under basal conditions.
So far, 21 patients with PINK1 homozygous or
compound heterozygous mutations have been re-
Figure 1. Top: Methyl-3-?-(4-?[123I]iodophenyl)tropane-2?-carboxylate SPECT scan of the patient; six regions of interest
(ROI), three in each hemisphere (ROI 1, 2, and 5 on the right; ROI 3, 4, and 6 on the left) are superimposed on the left
panel. ROI 1 and 3 correspond to the striatal region, ROI 2 and 4 to the putamen, and ROI 5 and 6 to the caudate nu-
cleus. Dopaminergic denervation is almost complete in the putamen, whereas the caudate nucleus is comparatively less
affected. Bottom: Analysis of regional radiolabeled123I-metaiodobenzylguanidine uptake shows a reduced metaiodoben-
zylguanidine activity in the laterobasal and inferior walls of the left ventricle compared with the upper mediastinum, in-
dicating partial ?-adrenergic denervation.
June (1 of 2) 2005
ported (table).1-5,9Although the phenotypic spectrum Download full-text
of PINK1 disease is rather wide, typical features of
PD predominate. The present case shows that ortho-
static hypotension (a rare occurrence) was associated
with postsynaptic sympathetic denervation, as ob-
served in typical PD. Excellent and sustained re-
sponse to levodopa therapy has been reported in all
patients with PINK1 disease; we observed here that
this response was still sustained after 15 years of
disease, when withdrawal produced a marked wors-
ening of motor condition.
Genotype-phenotype correlates in PINK1 disease
have not been fully elucidated. A large proportion of
mutations are missense changes, whose pathogenetic
role in sporadic cases remains unclear in the absence
of a functional assay on the protein. Bioinformatic
analysis of the PINK1 protein showed that alanine
168 is localized inside the conserved adenosine
triphosphate-binding region (amino acids 162 to
170), which is characterized by rich ?-sheet content
(figure 2). Mutation of this residue might influence
the local nonbonded interactions implied in adeno-
sine triphosphate/adenosine diphosphate binding
and therefore alter the kinase activity. This is partic-
ularly true in the specific mutation A168P because
proline is an amino acid with disruptive effects in
the hydrogen-bonding patterns of ?-helices and
?-sheets.10The identification of the role by which
different mutant PINK1 proteins produce their phe-
notypic aftermath will contribute to a better under-
standing of the pathogenesis of variants of EOP.
1. Valente EM, Abou-Sleiman PM, Caputo V, et al. Hereditary early-onset
Parkinson’s disease caused by mutations in PINK1. Science 2004;304:
2. Valente EM, Salvi S, Ialongo T, et al. PINK1 mutations are associated
with sporadic early-onset parkinsonism. Ann Neurol 2004;56:336–341.
3. Hatano Y, Li Y, Sato K, et al. Novel PINK1 mutations in early-onset
parkinsonism. Ann Neurol 2004;56:424–427.
4. Rohe CF, Montagna P, Breedveld G, Cortelli P, Oostra BA, Bonifati V.
Homozygous PINK1 C-terminus mutation causing early-onset parkin-
sonism. Ann Neurol 2004;56:427–431.
5. Rogaeva E, Johnson J, Lang AE, et al. Analysis of the PINK1 gene in a
large cohort of cases with Parkinson disease. Arch Neurol 2004;61:
6. Khan NL, Valente EM, Bentivoglio AR, et al. Clinical and subclinical
dopaminergic dysfunction in PARK6-linked parkinsonism: An 18F-dopa
PET study. Ann Neurol 2002;52:849–853.
7. Booij J, Tissingh G, Boer GJ, et al. [123I]FP-CIT SPECT shows a
pronounced decline of striatal dopamine transporter labelling in early
and advanced Parkinson’s disease. J Neurol Neurosurg Psychiatry
8. Shen J, Cookson MR. Mitochondria and dopamine: new insights into
recessive parkinsonism. Neuron 2004;43:301–304.
9. Hatano Y, Sato K, Elibol B, et al. PARK6-linked autosomal recessive
early-onset parkinsonism in Asian populations. Neurology 2004;63:
10. Ulrich SM, Kenski DM, Shokat KM. Engineering a ‘‘methionine clamp’’
into Src family kinases enhances specificity toward unnatural ATP
analogues. Biochemistry 2003;42:7915–21.
Figure 2. Model of the nucleotide phosphate-binding re-
gion of PINK1 in the presence of an adenosine triphos-
phate (ATP) ligand. The protein structure has been
obtained from ModBase (residues 151 to 501 modeled on
the PDB structure 1gjo as template). ATP has been posi-
tioned according to the experimental docking geometry
found in the structure of a homologous kinase complexed
with this ligand (PDB structure 1h1w) and subjected to
energy optimization. The protein is represented as ribbons,
residues 162 to 170 in the ATP-binding region, and ATP
is depicted as sticks (alanine 168 is highlighted by the or-
ange mesh and ATP is in green). The model has been ren-
dered with the program PyMOL (http://www.pymol.org).
Table Prevalence of clinical features in the 21 PINK1-positive
cases reported in literature
Clinical feature Prevalence (%)
Mean age at onset (range)
Excellent and sustained response to
Slow disease progression
Asymmetry at onset
Dystonia at onset
31.6 y (18 to 48)
For each feature, percentages were calculated on the total num-
ber of patients for whom clinical data were available.
June (1 of 2) 2005