- Email: [email protected]
PARK11 gene (GIGYF2) variants Asn56Ser and Asn457Thr are not pathogenic for Parkinson's disease
Parkinsonism and Related Disorders 15 (2009) 532–534
Contents lists available at ScienceDirect
Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis
PARK11 gene (GIGYF2) variants Asn56Ser and Asn457Thr are not pathogenic for Parkinson’s disease Alexander Zimprich a, *, Claudia Schulte b, Eva Reinthaler a, Dietrich Haubenberger a, Jo¨rg Balzar a, Peter Lichtner c, Salwa El Tawil d, S. Edris e, Thomas Foki a, Walter Pirker a, Regina Katzenschlager f, Gerhard Daniel g, Thomas Bru¨cke g, Eduard Auff a, Thomas Gasser b a
Department of Clinical Neurology, Medical University of Vienna, Vienna, Austria ¨ bingen, Tu ¨ bingen, Germany Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research, University of Tu Institute of Human Genetics, GSF National Research Centre for Environment and Health, Neuherberg, Germany d Department of Neurology, Ain Shams University, Cairo, Egypt e Department of Molecular Biology, Ain Shams University, Cairo, Egypt f Department of Neurology, SMZ-Ost Donauspital, Vienna, Austria g Department of Neurology, Wilhelminenspital, Vienna, Austria b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 December 2008 Received in revised form 9 January 2009 Accepted 26 January 2009
The GIGYF2 (Grb10-Interacting GYF Protein-2) gene has recently been proposed to be the responsible gene for the PARK11 locus. Ten different putative pathogenic variants were identified in cohorts of Parkinson’s disease (PD) patients from Italy and France. Among these variants Asn56Ser and Asn457Thr were found repeatedly. In the present study we screened 669 PD patients (predominantly of central European origin) and 1051 control individuals for the presence of these two variants. Asn56Ser was found in one patient with a positive family history of the disease and in one control individual. The affected sister of the patient did not carry this variant. Asn457Thr was found in one patient, who was exceptional for his Egyptian origin and in three control individuals. This variant was not found in 50 control individuals from Egypt. We conclude that neither of these two variants plays a major role in the pathogenesis of PD in our study population. Ó 2009 Elsevier Ltd. All rights reserved.
Keywords: GIGYF2 PARK11
1. Introduction Parkinson’ s disease (PD) [MIM 168600] is a neurodegenerative disorder, affecting 1–2% of the population over 65. Clinically, the disease is characterized by a triad of rigidity, resting tremor and bradykinesia [1]. Genetic factors are known to play an important role in the development of the disease [2]. Family based linkage analyses and subsequent candidate gene sequencing have identified six unequivocally causative genes for monogenic forms of PD. Mutations in the genes SNCA [MIM 163890] and LRRK2 [MIM 609007] cause autosomal dominant PD and the genes PARK2 (Parkin) [MIM 602544], PINK1 [MIM 608309], DJ-1 [MIM 602533], and ATP13A2 [MIM 610513] are responsible for autosomal recessive forms of PD. In addition to these clearly identified Parkinson’s genes more than 20 different chromosomal regions have been delineated
* Corresponding author. Universitaetsklinik fuer Neurologie, Allgemeines Krankenhaus der Stadt Wien, Waehringer Guertel 18–20, A-1090 Vienna, Austria. Tel.: þ43 1 40 400 6349; fax: þ43 1 40 400 3141. E-mail address: [email protected] (A. Zimprich). 1353-8020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.parkreldis.2009.01.005
which might contain susceptibility loci for the disease [3–8]. Yet, for none of these loci a responsible gene has been unambiguously identified to date. One of these susceptibility loci, designated as PARK11, on chromosome 2q36–37 was first detected in a genome wide linkage analysis in 160 families [5]. The locus was subsequently confirmed in two other linkage studies in 150 and 113 sib pairs with maximal LOD scores of 5,1 and 4.9 [9,10]. However, in a third study in European families (n ¼ 45) PARK11 could not be confirmed as a susceptibility locus [11]. Recently, the gene GIGYF2 (Grb10-Interacting GYF Protein-2), located within the PARK11 locus at the region of the highest LOD score has been proposed as the probable causative gene for PARK11 [12]. The arguments supporting this claim were also based on a good biological plausibility of GIGYF2 being a PD candidate gene. The GIGYF2 protein interacts with the Grb10 adaptor protein, which is involved in insulin signalling [13]. The insulin pathway has been previously associated with PD [14]. This prompted Lautier et al. [12] to perform a comprehensive sequence analysis of the GIGYF2 gene. Familial PD patients (n ¼ 249) and control individuals (n ¼ 227) from France and Italy were completely sequenced for 27 exons of the gene. The analysis revealed 10 different amino acid variations in
A. Zimprich et al. / Parkinsonism and Related Disorders 15 (2009) 532–534
12 PD patients which were not seen in control individuals. Notably, two variants, Asn56Ser and Asn457Thr were found repeatedly, in four and three cases respectively. Asn56Ser also segregated with the disease in a small family of two affected individuals. In the present study we attempted to screen for these two variants in 669 PD patients of predominantly Caucasian ethnicity and in 1051 healthy control individuals. 2. Materials and methods 2.1. Patients and controls 2.1.1. Austrian series The Austrian series comprised 360 patients (245 males (68%) and 115 females (32%)). They were recruited at the movement disorders clinic at the Department of Neurology, Medical University Vienna, as well as in affiliated clinics in Vienna on a consecutive basis (Department of Neurology, SMZ-Ost Donauspital, Vienna, and the Department of Neurology, Wilhelminenspital, Vienna). A positive family history for PD was reported from 94 patients (26%), as defined by at least one other affected first- or second-degree related family member. Mean age at onset of PD was 58.9 11.1 years. The origin of our patients was predominantly central European (348 Austrian, five North African, four Turkish, one Asian, one Greek and one Finnish). The clinical diagnosis of idiopathic PD was made by a movement disorders specialist, based on standard clinical criteria (UK Brain Bank criteria) [15]. Patients presenting atypical or secondary (e.g. vascular) parkinsonian disorders were excluded. Control subjects n ¼ 418 (238 males (57%), 180 females (43%)), with a mean age of 50.7 14.8 were recruited through the Department of Neurology, Medical University of Vienna, as subjects without known history of a neurological disorder, such as blood donors or non-blood-related companions or spouses of patients. 2.1.2. German series The German series comprised 309 patients (178 males (58%) 131 females (42%)). They were recruited by participating institutions in Munich and Tu¨bingen. Specialists in movement disorders examined the patients, and diagnosed them according to the UKPDS Brain Bank criteria. The mean age at onset of PD was 51.8 12.6 years. A positive family history for PD was reported from 45 patients (15%). A total of 633 healthy subjects (372 males (59%), 261 females (41%)) from the KORA Survey 2000 were used as control individuals. These controls were sampled as a part of a population-based representative cohort study from the city of Augsburg. The mean age at examination was of 53.3 12.0 years. In addition 50 control individuals from the City of Cairo, which were free of neurological symptoms, were tested for Asn457Thr. All probands from Germany, Austria and Egypt gave written informed consent. The local ethics committee approved the study. 2.2. Genotyping Probands were genotyped for the two variants by either of two methods. The Austrian samples were genotyped using a Taqman based allelic Discrimination assay. Primers and probes were designed using the Primer Express Software (Applied Biosystems). To validate the assay conditions DNAs from heterozygous carriers of the Asn56Ser and Asn457Thr variants were used as positive controls on all reaction plates. An aliquot of DNA was kindly provided by Dr. Stefano Goldwurm. The German samples were genotyped by primer extension of the PCR product, with detection of the allele-specific extension products by the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry method (Mass Array, Sequenom, San Diego, CA). Sequence information for primers and probes are available upon request.
3. Results The variant Asn56Ser was found in one of 669 screened PD patients in a heterozygous state. This female carrier was a patient from Austria with classical late onset PD. Age of onset was 59 years. She presented with resting tremor, rigidity and bradykinesia and responded well to levodopa. Disease duration was 18 years. Disease severity and progression did not differ from typical PD. The patient had a positive family history of PD. Her mother and two sisters were also affected by the disease. One sister was available for clinical examination and genetic testing. She presented with tremor, rigidity and bradykinesia and had a disease onset at 56 years. She did not carry Asn56Ser. The variant was also found in a heterozygous state in
533
one of 1051 tested control individuals (A healthy Austrian male, aged 77 years at the time of blood donation). Asn457Thr was found in a heterozygous state in one of 669 patients. This patient from Egypt had an age of onset of 46 years and presented with marked rigidity and bradykinesia but only slight resting tremor. He responded well to levodopa. Dopamine transporter imaging using b-CIT-single photon emission tomography showed nigrostriatal dopaminergic degeneration, compatible with idiopathic PD. He reported no family history of PD. Disease duration was 10 years. Disease severity and progression was within the range of classical PD. The same Asn457Thr variant was also found in a heterozygous state in one of 418 control individuals from Austria (female 40a at the time of blood donation) and in two of 633 control individuals from the German series (female 67a and male 72a at the time of blood donation). Control individuals from the City of Cairo, who were free of neurological symptoms (n ¼ 50) were tested negative for the Asn457Thr variant. To address the question of a possible digenic inheritance of GIGYF2 gene mutations with the LRRK2 gene we sequenced exon 41 of LRRK2 in the two patients carrying the GIGYF2 variants. No sequence variants were found. 4. Discussion GIGYF2 has recently been suggested as the probable causative gene for the PARK11 locus. In the present study we screened Caucasian and a few non-Caucasian PD patients and control individuals for two GIGYF2 mutations repeatedly detected in a previous study (Asn56Ser and Asn457Thr). Lack of segregation of Asn56Ser in two affected sisters, and the occurrence of both variants in control individuals weakens the case that these variants are pathogenetically relevant. In the case of Asn457Thr three control individuals harbored the variant and two of them were above the average age of onset, which makes it unlikely that these individuals are presymptomatic. Notably, the early disease onset of the patient harboring the 457Thr mutation (46 years) is interesting, as this would suggest that genetic factors might have a stronger contribution in this particular case. As the Asn457Thr patient originated from Egypt we tested 50 individuals from the City of Cairo, who were free of neurological symptoms. They all tested negative for this variant, which excludes that Asn457Thr is a frequent polymorphism in the Egyptian population. Asn56Ser was found in one patient and in one control individual. Two sisters and the mother were reported to be affected by the disease. Thus a genetic basis with a dominant gene might be assumed to be responsible for the disease in this family. As the variant was not found in the affected sister, a pathogenic role for Asn56Ser is therefore highly unlikely. In the original study by Lautier et al. [12] one patient was found to carry simultaneously a GIGYF2 gene mutation (Ile278Val) and a putative LRRK2 gene mutation (Ile1371Val). Interestingly, this patient also had an early onset (33a) and a severe clinical course. Digenic inheritance with an additive effect of GIGYF2 and LRRK2 gene mutations was therefore suggested as a possible pathogenetic mechanism. We sequenced exon 41 of the LRRK2 gene in the two patients. LRRK2 exon 41 was chosen because a number of important pathogenic mutations are known to occur within this particular exon. We found no sequence variation. Of course, with the absence of a mutation in LRRK2 exon 41 such a pathogenetic mechanism cannot be excluded. Another LRRK2 exon or another PD gene might still harbor a mutation. Very recently the first replication attempt of the association of GIGYF2 and Parkinson’s disease was published [16]. In this study a large series of Portuguese and North American patients (n ¼ 724) and ethnically matched control individuals (n ¼ 911) were sequenced for
534
A. Zimprich et al. / Parkinsonism and Related Disorders 15 (2009) 532–534
all exons of the gene. A total of 46 variants were identified, with most of them being present in patients and controls and none of the variants was found to be significantly enriched in the patient group. Among these, four variants described as potentially pathogenic by Lautier et al. were found in their control samples (p.N478T, p.L1230_Q1237del, c.3689-3712del24, p.H1192R). Interestingly, neither Asn56Ser nor Asn457Thr were found in this study. Taken together, our results and the findings from Bras et al. do not support GIGYF2 as a PD susceptibility gene. In the initial study by Lautier et al. 10 variants were suggested as being pathogenic; six are now found to be present in control individuals, some of them even more frequent in control individuals. It is noteworthy that in the initial study only a relatively small control group was screened for the presence of the variants (n ¼ 227). Considering the low frequency of the variants in our study population it is conceivable that they had been missed in the initial study. However, a minor role of GIGYF2 variants in the pathogenesis of PD cannot be ruled out entirely at this stage. Sequencing of the complete gene in more patients and control individuals of different ethnicities will help to answer this question. Acknowledgements The KORA (Cooperative Health Research in the Region of Augsburg, Germany) group consists of H.E. Wichmann (speaker), H. Lo¨wel, C. Meisinger, T. Illig, R. Holle, J. Hohn, and their coworkers, who are responsible for the design and conduct of the KORA studies. The authors thank the patients and controls for their participation. The study was funded by the German National Genome Network (NGFNplus; German Ministry for Education and Research, #01GS08134). References [1] Lang AE, Lozano AM. Parkinson’s disease. First of two parts. N Engl J Med 1998;339(15):1044–53. 8 (Review).
[2] Payami H, Zareparsi S. Genetic epidemiology of Parkinson’s disease. J Geriatr Psychiatry Neurol 1998;11(2):98–106 (Review). [3] DeStefano AL, Golbe LI, Mark MH, Lazzarini AM, Maher NE, Saint-Hilaire M, et al. Genome-wide scan for Parkinson’s disease: the GenePD Study. Neurology 2001;57(6):1124–6. [4] Scott WK, Nance MA, Watts RL, Hubble JP, Koller WC, Lyons K, et al. Complete genomic screen in Parkinson disease: evidence for multiple genes. JAMA 2001;286(18):2239–44. [5] Pankratz N, Nichols WC, Uniacke SK, Halter C, Rudolph A, Shults C, et al. Genome screen to identify susceptibility genes for Parkinson disease in a sample without parkin mutations. Am J Hum Genet 2002;71(1): 124–35. [6] Hicks AA, Pe´tursson H, Jo´nsson T, Stefa´nsson H, Jo´hannsdo´ttir HS, Sainz J, et al. A susceptibility gene for late-onset idiopathic Parkinson’s disease. Ann Neurol 2002;52(5):549–55. [7] Li YJ, Scott WK, Hedges DJ, Zhang F, Gaskell PC, Nance MA, et al. Age at onset in two common neurodegenerative diseases is genetically controlled. Am J Hum Genet 2002;70(4):985–93. [8] Martinez M, Brice A, Vaughan JR, Zimprich A, Breteler MM, Meco G, et al. Genome-wide scan linkage analysis for Parkinson’s disease: the European genetic study of Parkinson’s disease. J Med Genet 2004;41(12): 900–7. [9] Pankratz N, Nichols WC, Uniacke SK, Halter C, Rudolph A, Shults C, et al. Significant linkage of Parkinson disease to chromosome 2q36–37. Am J Hum Genet 2003;72(4):1053–7. [10] Pankratz N, Nichols WC, Uniacke SK, Halter C, Murrell J, Rudolph A, et al. Genome-wide linkage analysis and evidence of gene-by-gene interactions in a sample of 362 multiplex Parkinson disease families. Hum Mol Genet 2003;12(20):2599–608. [11] Prestel J, Sharma M, Leitner P, Zimprich A, Vaughan JR, Du¨rr A, et al. PARK11 is not linked with Parkinson’s disease in European families. Eur J Hum Genet 2005;13(2):193–7. [12] Lautier C, Goldwurm S, Du¨rr A, Giovannone B, Tsiaras WG, Pezzoli G, et al. Mutations in the GIGYF2 (TNRC15) gene at the PARK11 locus in familial Parkinson disease. Am J Hum Genet 2008;82(4):822–33. [13] Giovannone B, Lee E, Laviola L, Giorgino F, Cleveland KA, Smith RJ. Two novel proteins that are linked to insulin-like growth factor (IGF-I) receptors by the Grb10 adapter and modulate IGF-I signaling. J Biol Chem 2003;278(34): 31564–73. [14] Craft S, Watson GS. Insulin and neurodegenerative disease: shared and specific mechanisms. Lancet Neurol 2004;3(3):169–78 (Review). [15] Hughes AJ, Daniel SE, Kilford L, Lees AJ. Accuracy of clinical diagnosis of idiopathic Parkinson’s disease: a clinico-pathological study of 100 cases. J Neurol Neurosurg Psychiatry 1992;55:181–4. [16] Bras J, Simo´n-Sa´nchez J, Federoff M, Morgadinho A, Januario C, Ribeiro M, et al. Lack of replication of association between GIGYF2 variants and Parkinson disease. Hum Mol Genet 2008. Oct 15 [Epub ahead of print].
Contents lists available at ScienceDirect
Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis
PARK11 gene (GIGYF2) variants Asn56Ser and Asn457Thr are not pathogenic for Parkinson’s disease Alexander Zimprich a, *, Claudia Schulte b, Eva Reinthaler a, Dietrich Haubenberger a, Jo¨rg Balzar a, Peter Lichtner c, Salwa El Tawil d, S. Edris e, Thomas Foki a, Walter Pirker a, Regina Katzenschlager f, Gerhard Daniel g, Thomas Bru¨cke g, Eduard Auff a, Thomas Gasser b a
Department of Clinical Neurology, Medical University of Vienna, Vienna, Austria ¨ bingen, Tu ¨ bingen, Germany Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research, University of Tu Institute of Human Genetics, GSF National Research Centre for Environment and Health, Neuherberg, Germany d Department of Neurology, Ain Shams University, Cairo, Egypt e Department of Molecular Biology, Ain Shams University, Cairo, Egypt f Department of Neurology, SMZ-Ost Donauspital, Vienna, Austria g Department of Neurology, Wilhelminenspital, Vienna, Austria b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 December 2008 Received in revised form 9 January 2009 Accepted 26 January 2009
The GIGYF2 (Grb10-Interacting GYF Protein-2) gene has recently been proposed to be the responsible gene for the PARK11 locus. Ten different putative pathogenic variants were identified in cohorts of Parkinson’s disease (PD) patients from Italy and France. Among these variants Asn56Ser and Asn457Thr were found repeatedly. In the present study we screened 669 PD patients (predominantly of central European origin) and 1051 control individuals for the presence of these two variants. Asn56Ser was found in one patient with a positive family history of the disease and in one control individual. The affected sister of the patient did not carry this variant. Asn457Thr was found in one patient, who was exceptional for his Egyptian origin and in three control individuals. This variant was not found in 50 control individuals from Egypt. We conclude that neither of these two variants plays a major role in the pathogenesis of PD in our study population. Ó 2009 Elsevier Ltd. All rights reserved.
Keywords: GIGYF2 PARK11
1. Introduction Parkinson’ s disease (PD) [MIM 168600] is a neurodegenerative disorder, affecting 1–2% of the population over 65. Clinically, the disease is characterized by a triad of rigidity, resting tremor and bradykinesia [1]. Genetic factors are known to play an important role in the development of the disease [2]. Family based linkage analyses and subsequent candidate gene sequencing have identified six unequivocally causative genes for monogenic forms of PD. Mutations in the genes SNCA [MIM 163890] and LRRK2 [MIM 609007] cause autosomal dominant PD and the genes PARK2 (Parkin) [MIM 602544], PINK1 [MIM 608309], DJ-1 [MIM 602533], and ATP13A2 [MIM 610513] are responsible for autosomal recessive forms of PD. In addition to these clearly identified Parkinson’s genes more than 20 different chromosomal regions have been delineated
* Corresponding author. Universitaetsklinik fuer Neurologie, Allgemeines Krankenhaus der Stadt Wien, Waehringer Guertel 18–20, A-1090 Vienna, Austria. Tel.: þ43 1 40 400 6349; fax: þ43 1 40 400 3141. E-mail address: [email protected] (A. Zimprich). 1353-8020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.parkreldis.2009.01.005
which might contain susceptibility loci for the disease [3–8]. Yet, for none of these loci a responsible gene has been unambiguously identified to date. One of these susceptibility loci, designated as PARK11, on chromosome 2q36–37 was first detected in a genome wide linkage analysis in 160 families [5]. The locus was subsequently confirmed in two other linkage studies in 150 and 113 sib pairs with maximal LOD scores of 5,1 and 4.9 [9,10]. However, in a third study in European families (n ¼ 45) PARK11 could not be confirmed as a susceptibility locus [11]. Recently, the gene GIGYF2 (Grb10-Interacting GYF Protein-2), located within the PARK11 locus at the region of the highest LOD score has been proposed as the probable causative gene for PARK11 [12]. The arguments supporting this claim were also based on a good biological plausibility of GIGYF2 being a PD candidate gene. The GIGYF2 protein interacts with the Grb10 adaptor protein, which is involved in insulin signalling [13]. The insulin pathway has been previously associated with PD [14]. This prompted Lautier et al. [12] to perform a comprehensive sequence analysis of the GIGYF2 gene. Familial PD patients (n ¼ 249) and control individuals (n ¼ 227) from France and Italy were completely sequenced for 27 exons of the gene. The analysis revealed 10 different amino acid variations in
A. Zimprich et al. / Parkinsonism and Related Disorders 15 (2009) 532–534
12 PD patients which were not seen in control individuals. Notably, two variants, Asn56Ser and Asn457Thr were found repeatedly, in four and three cases respectively. Asn56Ser also segregated with the disease in a small family of two affected individuals. In the present study we attempted to screen for these two variants in 669 PD patients of predominantly Caucasian ethnicity and in 1051 healthy control individuals. 2. Materials and methods 2.1. Patients and controls 2.1.1. Austrian series The Austrian series comprised 360 patients (245 males (68%) and 115 females (32%)). They were recruited at the movement disorders clinic at the Department of Neurology, Medical University Vienna, as well as in affiliated clinics in Vienna on a consecutive basis (Department of Neurology, SMZ-Ost Donauspital, Vienna, and the Department of Neurology, Wilhelminenspital, Vienna). A positive family history for PD was reported from 94 patients (26%), as defined by at least one other affected first- or second-degree related family member. Mean age at onset of PD was 58.9 11.1 years. The origin of our patients was predominantly central European (348 Austrian, five North African, four Turkish, one Asian, one Greek and one Finnish). The clinical diagnosis of idiopathic PD was made by a movement disorders specialist, based on standard clinical criteria (UK Brain Bank criteria) [15]. Patients presenting atypical or secondary (e.g. vascular) parkinsonian disorders were excluded. Control subjects n ¼ 418 (238 males (57%), 180 females (43%)), with a mean age of 50.7 14.8 were recruited through the Department of Neurology, Medical University of Vienna, as subjects without known history of a neurological disorder, such as blood donors or non-blood-related companions or spouses of patients. 2.1.2. German series The German series comprised 309 patients (178 males (58%) 131 females (42%)). They were recruited by participating institutions in Munich and Tu¨bingen. Specialists in movement disorders examined the patients, and diagnosed them according to the UKPDS Brain Bank criteria. The mean age at onset of PD was 51.8 12.6 years. A positive family history for PD was reported from 45 patients (15%). A total of 633 healthy subjects (372 males (59%), 261 females (41%)) from the KORA Survey 2000 were used as control individuals. These controls were sampled as a part of a population-based representative cohort study from the city of Augsburg. The mean age at examination was of 53.3 12.0 years. In addition 50 control individuals from the City of Cairo, which were free of neurological symptoms, were tested for Asn457Thr. All probands from Germany, Austria and Egypt gave written informed consent. The local ethics committee approved the study. 2.2. Genotyping Probands were genotyped for the two variants by either of two methods. The Austrian samples were genotyped using a Taqman based allelic Discrimination assay. Primers and probes were designed using the Primer Express Software (Applied Biosystems). To validate the assay conditions DNAs from heterozygous carriers of the Asn56Ser and Asn457Thr variants were used as positive controls on all reaction plates. An aliquot of DNA was kindly provided by Dr. Stefano Goldwurm. The German samples were genotyped by primer extension of the PCR product, with detection of the allele-specific extension products by the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry method (Mass Array, Sequenom, San Diego, CA). Sequence information for primers and probes are available upon request.
3. Results The variant Asn56Ser was found in one of 669 screened PD patients in a heterozygous state. This female carrier was a patient from Austria with classical late onset PD. Age of onset was 59 years. She presented with resting tremor, rigidity and bradykinesia and responded well to levodopa. Disease duration was 18 years. Disease severity and progression did not differ from typical PD. The patient had a positive family history of PD. Her mother and two sisters were also affected by the disease. One sister was available for clinical examination and genetic testing. She presented with tremor, rigidity and bradykinesia and had a disease onset at 56 years. She did not carry Asn56Ser. The variant was also found in a heterozygous state in
533
one of 1051 tested control individuals (A healthy Austrian male, aged 77 years at the time of blood donation). Asn457Thr was found in a heterozygous state in one of 669 patients. This patient from Egypt had an age of onset of 46 years and presented with marked rigidity and bradykinesia but only slight resting tremor. He responded well to levodopa. Dopamine transporter imaging using b-CIT-single photon emission tomography showed nigrostriatal dopaminergic degeneration, compatible with idiopathic PD. He reported no family history of PD. Disease duration was 10 years. Disease severity and progression was within the range of classical PD. The same Asn457Thr variant was also found in a heterozygous state in one of 418 control individuals from Austria (female 40a at the time of blood donation) and in two of 633 control individuals from the German series (female 67a and male 72a at the time of blood donation). Control individuals from the City of Cairo, who were free of neurological symptoms (n ¼ 50) were tested negative for the Asn457Thr variant. To address the question of a possible digenic inheritance of GIGYF2 gene mutations with the LRRK2 gene we sequenced exon 41 of LRRK2 in the two patients carrying the GIGYF2 variants. No sequence variants were found. 4. Discussion GIGYF2 has recently been suggested as the probable causative gene for the PARK11 locus. In the present study we screened Caucasian and a few non-Caucasian PD patients and control individuals for two GIGYF2 mutations repeatedly detected in a previous study (Asn56Ser and Asn457Thr). Lack of segregation of Asn56Ser in two affected sisters, and the occurrence of both variants in control individuals weakens the case that these variants are pathogenetically relevant. In the case of Asn457Thr three control individuals harbored the variant and two of them were above the average age of onset, which makes it unlikely that these individuals are presymptomatic. Notably, the early disease onset of the patient harboring the 457Thr mutation (46 years) is interesting, as this would suggest that genetic factors might have a stronger contribution in this particular case. As the Asn457Thr patient originated from Egypt we tested 50 individuals from the City of Cairo, who were free of neurological symptoms. They all tested negative for this variant, which excludes that Asn457Thr is a frequent polymorphism in the Egyptian population. Asn56Ser was found in one patient and in one control individual. Two sisters and the mother were reported to be affected by the disease. Thus a genetic basis with a dominant gene might be assumed to be responsible for the disease in this family. As the variant was not found in the affected sister, a pathogenic role for Asn56Ser is therefore highly unlikely. In the original study by Lautier et al. [12] one patient was found to carry simultaneously a GIGYF2 gene mutation (Ile278Val) and a putative LRRK2 gene mutation (Ile1371Val). Interestingly, this patient also had an early onset (33a) and a severe clinical course. Digenic inheritance with an additive effect of GIGYF2 and LRRK2 gene mutations was therefore suggested as a possible pathogenetic mechanism. We sequenced exon 41 of the LRRK2 gene in the two patients. LRRK2 exon 41 was chosen because a number of important pathogenic mutations are known to occur within this particular exon. We found no sequence variation. Of course, with the absence of a mutation in LRRK2 exon 41 such a pathogenetic mechanism cannot be excluded. Another LRRK2 exon or another PD gene might still harbor a mutation. Very recently the first replication attempt of the association of GIGYF2 and Parkinson’s disease was published [16]. In this study a large series of Portuguese and North American patients (n ¼ 724) and ethnically matched control individuals (n ¼ 911) were sequenced for
534
A. Zimprich et al. / Parkinsonism and Related Disorders 15 (2009) 532–534
all exons of the gene. A total of 46 variants were identified, with most of them being present in patients and controls and none of the variants was found to be significantly enriched in the patient group. Among these, four variants described as potentially pathogenic by Lautier et al. were found in their control samples (p.N478T, p.L1230_Q1237del, c.3689-3712del24, p.H1192R). Interestingly, neither Asn56Ser nor Asn457Thr were found in this study. Taken together, our results and the findings from Bras et al. do not support GIGYF2 as a PD susceptibility gene. In the initial study by Lautier et al. 10 variants were suggested as being pathogenic; six are now found to be present in control individuals, some of them even more frequent in control individuals. It is noteworthy that in the initial study only a relatively small control group was screened for the presence of the variants (n ¼ 227). Considering the low frequency of the variants in our study population it is conceivable that they had been missed in the initial study. However, a minor role of GIGYF2 variants in the pathogenesis of PD cannot be ruled out entirely at this stage. Sequencing of the complete gene in more patients and control individuals of different ethnicities will help to answer this question. Acknowledgements The KORA (Cooperative Health Research in the Region of Augsburg, Germany) group consists of H.E. Wichmann (speaker), H. Lo¨wel, C. Meisinger, T. Illig, R. Holle, J. Hohn, and their coworkers, who are responsible for the design and conduct of the KORA studies. The authors thank the patients and controls for their participation. The study was funded by the German National Genome Network (NGFNplus; German Ministry for Education and Research, #01GS08134). References [1] Lang AE, Lozano AM. Parkinson’s disease. First of two parts. N Engl J Med 1998;339(15):1044–53. 8 (Review).
[2] Payami H, Zareparsi S. Genetic epidemiology of Parkinson’s disease. J Geriatr Psychiatry Neurol 1998;11(2):98–106 (Review). [3] DeStefano AL, Golbe LI, Mark MH, Lazzarini AM, Maher NE, Saint-Hilaire M, et al. Genome-wide scan for Parkinson’s disease: the GenePD Study. Neurology 2001;57(6):1124–6. [4] Scott WK, Nance MA, Watts RL, Hubble JP, Koller WC, Lyons K, et al. Complete genomic screen in Parkinson disease: evidence for multiple genes. JAMA 2001;286(18):2239–44. [5] Pankratz N, Nichols WC, Uniacke SK, Halter C, Rudolph A, Shults C, et al. Genome screen to identify susceptibility genes for Parkinson disease in a sample without parkin mutations. Am J Hum Genet 2002;71(1): 124–35. [6] Hicks AA, Pe´tursson H, Jo´nsson T, Stefa´nsson H, Jo´hannsdo´ttir HS, Sainz J, et al. A susceptibility gene for late-onset idiopathic Parkinson’s disease. Ann Neurol 2002;52(5):549–55. [7] Li YJ, Scott WK, Hedges DJ, Zhang F, Gaskell PC, Nance MA, et al. Age at onset in two common neurodegenerative diseases is genetically controlled. Am J Hum Genet 2002;70(4):985–93. [8] Martinez M, Brice A, Vaughan JR, Zimprich A, Breteler MM, Meco G, et al. Genome-wide scan linkage analysis for Parkinson’s disease: the European genetic study of Parkinson’s disease. J Med Genet 2004;41(12): 900–7. [9] Pankratz N, Nichols WC, Uniacke SK, Halter C, Rudolph A, Shults C, et al. Significant linkage of Parkinson disease to chromosome 2q36–37. Am J Hum Genet 2003;72(4):1053–7. [10] Pankratz N, Nichols WC, Uniacke SK, Halter C, Murrell J, Rudolph A, et al. Genome-wide linkage analysis and evidence of gene-by-gene interactions in a sample of 362 multiplex Parkinson disease families. Hum Mol Genet 2003;12(20):2599–608. [11] Prestel J, Sharma M, Leitner P, Zimprich A, Vaughan JR, Du¨rr A, et al. PARK11 is not linked with Parkinson’s disease in European families. Eur J Hum Genet 2005;13(2):193–7. [12] Lautier C, Goldwurm S, Du¨rr A, Giovannone B, Tsiaras WG, Pezzoli G, et al. Mutations in the GIGYF2 (TNRC15) gene at the PARK11 locus in familial Parkinson disease. Am J Hum Genet 2008;82(4):822–33. [13] Giovannone B, Lee E, Laviola L, Giorgino F, Cleveland KA, Smith RJ. Two novel proteins that are linked to insulin-like growth factor (IGF-I) receptors by the Grb10 adapter and modulate IGF-I signaling. J Biol Chem 2003;278(34): 31564–73. [14] Craft S, Watson GS. Insulin and neurodegenerative disease: shared and specific mechanisms. Lancet Neurol 2004;3(3):169–78 (Review). [15] Hughes AJ, Daniel SE, Kilford L, Lees AJ. Accuracy of clinical diagnosis of idiopathic Parkinson’s disease: a clinico-pathological study of 100 cases. J Neurol Neurosurg Psychiatry 1992;55:181–4. [16] Bras J, Simo´n-Sa´nchez J, Federoff M, Morgadinho A, Januario C, Ribeiro M, et al. Lack of replication of association between GIGYF2 variants and Parkinson disease. Hum Mol Genet 2008. Oct 15 [Epub ahead of print].