Ceruloplasmin gene variations and substantia nigra hyperechogenicity in Parkinson disease.
BACKGROUND
Transcranial ultrasound may be used to detect increased iron levels of the substantia nigra (SN) in patients with Parkinson disease (PD) and in control subjects. It is not known whether iron accumulation in PD is a primary or secondary phenomenon. However, sequence variations in genes involved in iron metabolism have been linked to basal ganglia disorders. One of these is ceruloplasmin (Cp), which is vitally involved in iron transport across the cell membrane.


METHODS
One hundred seventy-six patients with PD according to the UK Brain Bank criteria and 180 ethnically matched control subjects, who were previously examined for SN iron signal changes by transcranial ultrasound, were examined for mutations in the Cp gene using denaturing high-performance liquid chromatography and subsequent sequencing for verification of unequivocal signals. Immunohistochemistry of PD midbrains was performed to examine the presence of Cp in Lewy bodies.


RESULTS
Five novel missense variations were detected. One of these (I63T) was found in a single PD patient. A known variation (D554E) was significantly associated with PD and the ultrasound marker for increased SN iron levels. Moreover, a third sequence variation (R793H) was found to segregate with the ultrasound marker for increased iron levels in patients and control subjects. Immunohistochemistry demonstrated that Cp co-localizes with Lewy bodies in PD.


CONCLUSIONS
Detection of sequence variations in a single Parkinson disease (PD) patient or associated with the ultrasound marker for increased substantia nigra iron levels and the presence of ceruloplasmin (Cp) immunoreactivity in Lewy bodies underline a suspected role for Cp in the pathogenesis of PD. Further functional analyses are warranted to investigate whether these variations are causally linked to the complex pathogenesis of PD in a subset of cases.
Hochstrasser
H
H
Institute for Medical Genetics, University of Tuebingen, Germany.
Bauer
P
P
Walter
U
U
Behnke
S
S
Spiegel
J
J
Csoti
I
I
Zeiler
B
B
Bornemann
A
A
Pahnke
J
J
Becker
G
G
Riess
O
O
Berg
D
D
D000368:Aged; D019943:Amino Acid Substitution; D002570:Ceruloplasmin / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D004252:DNA Mutational Analysis; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007501:Iron / Q000032:analysis*; D016631:Lewy Bodies / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017354:Point Mutation; D012150:Polymorphism, Restriction Fragment Length; D013378:Substantia Nigra / Q000737:chemistry* / Q000000981:diagnostic imaging; D017585:Ultrasonography, Doppler, Transcranial
D007501:Iron; D002570:Ceruloplasmin