Although in the last two decades there has been considerable progress in understanding the geneti... more Although in the last two decades there has been considerable progress in understanding the genetic basis of Parkinson's disease (PD), the majority of PD is sporadic and its genetic causes are largely unknown. In an attempt to identify novel genetic causes of PD, whole-exome sequencing and subsequent analyses were performed in a family featuring late-onset PD with cognitive impairment. A novel genetic variant (p.Arg610Gly) in the GIGYF2 gene, previously known to be associated with PD, was identified as potential disease-causing mutation. The GIGYF2 p.Arg610Gly mutation situated in the GYF domain of the encoding protein was predicted to be pathogenic and to disrupt the GYF's ligand-binding abilities. Although further research is still required, this finding may shed light on the GIGYF2-associated mechanisms that lead to PD and suggests insulin dysregulation as a disease-specific mechanism for both PD and cognitive dysfunction.Journal of Human Genetics advance online publicatio...
Latent transforming growth factor (TGF) beta-binding protein 2 (LTBP2) is an extracellular matrix... more Latent transforming growth factor (TGF) beta-binding protein 2 (LTBP2) is an extracellular matrix (ECM) protein that associates with fibrillin-1 containing microfibrils. Various factors prompted considering LTBP2 in the etiology of isolated ectopia lentis and associated conditions such as Weill-Marchesani syndrome (WMS) and Marfan syndrome (MFS). LTBP2 was screened in 30 unrelated Iranian patients. Mutations were found only in one WMS proband and one MFS proband. Homozygous c.3529G>A (p.Val1177Met) was shown to cause autosomal recessive WMS or WM-like syndrome by several approaches, including homozygosity mapping. Light, fluorescent, and electron microscopy evidenced disruptions of the microfibrillar network in the ECM of the proband's skin. In conjunction with recent findings regarding other ECM proteins, the results presented strongly support the contention that anomalies in WMS patients are due to disruptions in the ECM. Heterozygous c.1642C >T (p.Arg548*) possibly contributed to MFS-related phenotypes, including ocular manifestations, mitral valve prolapse, and pectus excavatum, but was not cause of MFS.
Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal domin... more Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal dominant form of parkinsonism. To identify mutations causing Parkinson's disease (PD) in a cohort of North Americans with familial PD. We sequenced exons 1-51 of LRRK2 in 79 unrelated North American PD patients reporting a family history of the disease. One patient had a missense mutation (Thr2356Ile) while two others had the common Gly2019Ser mutation. In addition, 1 patient had a 4-bp deletion in close proximity to the exon 19 splice donor (IVS20+4delGTAA) that in vitro abrogates normal splicing. Our observations in the 79 North American patients indicate that mutations in LRRK2 are associated with approximately 5% of PD cases with a positive family history. The results also show that G2019S represents approximately half of the LRRK2 mutations in United States PD cases with a family history of the disease. We have identified two novel mutations in LRRK2.
During the last few years several loci have been linked to Mendelian forms of Parkinson's dis... more During the last few years several loci have been linked to Mendelian forms of Parkinson's disease (PD). To date, 5 causative genes of 10 identified loci are known, and they have provided enormous insight into the molecular pathways involved in this common neurodegenerative disorder. One of the recently identified loci, PARK8, causes autosomal dominant PD with, apparently, various degrees of abnormal deposition of alpha-synuclein or tau in the neuronal cells in the pedigrees currently reported. We genetically characterized four Basque families and found evidence for linkage of autosomal dominant PD to the PARK8 locus, with a maximum 2-point logarithm of odds score of 3.21 (theta = 0.00) for marker D12S345. The clinical features of these families are those of typical PD, including good response to levodopa therapy, rigidity, and akinesia, and a mean age of 55 years at disease onset.
There is growing evidence in the scientific literature for shared risk and overlapping disease me... more There is growing evidence in the scientific literature for shared risk and overlapping disease mechanisms in the development of cancer and Parkinson disease (PD). This association has recently been highlighted with respect to melanoma and PD. Therefore, we review and discuss the literature concerning this unexplained link. A striking overlap is observed in the tyrosine and L-dopa biosynthetic pathways suggesting a common disease mechanism associated with these 2 heterogeneous disorders that warrants further investigation.
In 2004 it was first shown that mutations in LRRK2 can cause Parkinson's disease. This initia... more In 2004 it was first shown that mutations in LRRK2 can cause Parkinson's disease. This initial discovery was quickly followed by the observation that a single particular mutation is a relatively common cause of Parkinson's disease across varied populations. Further genetic investigation has revealed a variety of genetic ties to Parkinson's disease across this gene. These include common alleles with quite broad effects on risk, likely through both alterations at the protein sequence level, and in the context of expression. A great deal of functional characterization of LRRK2 and disease-causing mutations in this protein has occurred over the last 9 years, and considerable progress has been made. Particular attention has been paid to the kinase activity of LRRK2 as a therapeutic target, and while it is no means certain that this is viable target it is likely that this hypothesis will be tested in clinical trials sooner rather than later. We believe that the future goals fo...
In addition to the four well-confirmed genes linked to early-onset Parkinson disease (PD) (SNCA, ... more In addition to the four well-confirmed genes linked to early-onset Parkinson disease (PD) (SNCA, PARKIN, DJ-1, and PINK1), mutations in the leucine-rich repeat kinase 2 gene (LRRK2) have recently been identified in families with autosomal dominant late-onset PD. To perform mutation analysis of LRRK2 in probands of families showing dominant inheritance of PD and to conduct a case control association study to test the hypothesis that common coding variations might be associated with increased susceptibility to PD. All 51 LRRK2 coding exons were sequenced in 23 probands and the mutation frequencies were evaluated in 180 neurologically normal control subjects. For the association study the authors genotyped four coding LRRK2 polymorphisms in 250 normal control subjects and 121 patients with PD (predominantly white patients of Canadian origin), 84% of whom had age at onset before 50 years and 42% had a positive family history. The authors identified three probands with heterozygous LRRK2 mutations: two of them have the known G2019S substitution and one proband has a novel I1371V substitution. Mutation analysis of a large family demonstrated complete segregation of the G2019S with PD. However, there was no association between PD and any of the four polymorphisms at the allelic or genotypic levels (p > 0.17). Furthermore, the authors did not detect a modifying effect for any genotype or of APOE genotypes upon the age at onset in the PD group (p > 0.20). The results support the prior suggestion that LRRK2 mutations cause PD. The disease in the families reported here presents a phenotype indistinguishable from typical PD. All three families demonstrate a very variable age at onset that is not explained by APOE genotypes. The common coding variations in the LRRK2 gene neither constitute strong PD risk factors nor modify the age at onset; however, the possibility of a modest risk effect remains to be assessed in large datasets.
Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal domin... more Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal dominant form of parkinsonism. To identify mutations causing Parkinson's disease (PD) in a cohort of North Americans with familial PD. We sequenced exons 1-51 of LRRK2 in 79 unrelated North American PD patients reporting a family history of the disease. One patient had a missense mutation (Thr2356Ile) while two others had the common Gly2019Ser mutation. In addition, 1 patient had a 4-bp deletion in close proximity to the exon 19 splice donor (IVS20+4delGTAA) that in vitro abrogates normal splicing. Our observations in the 79 North American patients indicate that mutations in LRRK2 are associated with approximately 5% of PD cases with a positive family history. The results also show that G2019S represents approximately half of the LRRK2 mutations in United States PD cases with a family history of the disease. We have identified two novel mutations in LRRK2.
Although in the last two decades there has been considerable progress in understanding the geneti... more Although in the last two decades there has been considerable progress in understanding the genetic basis of Parkinson's disease (PD), the majority of PD is sporadic and its genetic causes are largely unknown. In an attempt to identify novel genetic causes of PD, whole-exome sequencing and subsequent analyses were performed in a family featuring late-onset PD with cognitive impairment. A novel genetic variant (p.Arg610Gly) in the GIGYF2 gene, previously known to be associated with PD, was identified as potential disease-causing mutation. The GIGYF2 p.Arg610Gly mutation situated in the GYF domain of the encoding protein was predicted to be pathogenic and to disrupt the GYF's ligand-binding abilities. Although further research is still required, this finding may shed light on the GIGYF2-associated mechanisms that lead to PD and suggests insulin dysregulation as a disease-specific mechanism for both PD and cognitive dysfunction.Journal of Human Genetics advance online publicatio...
Latent transforming growth factor (TGF) beta-binding protein 2 (LTBP2) is an extracellular matrix... more Latent transforming growth factor (TGF) beta-binding protein 2 (LTBP2) is an extracellular matrix (ECM) protein that associates with fibrillin-1 containing microfibrils. Various factors prompted considering LTBP2 in the etiology of isolated ectopia lentis and associated conditions such as Weill-Marchesani syndrome (WMS) and Marfan syndrome (MFS). LTBP2 was screened in 30 unrelated Iranian patients. Mutations were found only in one WMS proband and one MFS proband. Homozygous c.3529G>A (p.Val1177Met) was shown to cause autosomal recessive WMS or WM-like syndrome by several approaches, including homozygosity mapping. Light, fluorescent, and electron microscopy evidenced disruptions of the microfibrillar network in the ECM of the proband's skin. In conjunction with recent findings regarding other ECM proteins, the results presented strongly support the contention that anomalies in WMS patients are due to disruptions in the ECM. Heterozygous c.1642C >T (p.Arg548*) possibly contributed to MFS-related phenotypes, including ocular manifestations, mitral valve prolapse, and pectus excavatum, but was not cause of MFS.
Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal domin... more Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal dominant form of parkinsonism. To identify mutations causing Parkinson's disease (PD) in a cohort of North Americans with familial PD. We sequenced exons 1-51 of LRRK2 in 79 unrelated North American PD patients reporting a family history of the disease. One patient had a missense mutation (Thr2356Ile) while two others had the common Gly2019Ser mutation. In addition, 1 patient had a 4-bp deletion in close proximity to the exon 19 splice donor (IVS20+4delGTAA) that in vitro abrogates normal splicing. Our observations in the 79 North American patients indicate that mutations in LRRK2 are associated with approximately 5% of PD cases with a positive family history. The results also show that G2019S represents approximately half of the LRRK2 mutations in United States PD cases with a family history of the disease. We have identified two novel mutations in LRRK2.
During the last few years several loci have been linked to Mendelian forms of Parkinson's dis... more During the last few years several loci have been linked to Mendelian forms of Parkinson's disease (PD). To date, 5 causative genes of 10 identified loci are known, and they have provided enormous insight into the molecular pathways involved in this common neurodegenerative disorder. One of the recently identified loci, PARK8, causes autosomal dominant PD with, apparently, various degrees of abnormal deposition of alpha-synuclein or tau in the neuronal cells in the pedigrees currently reported. We genetically characterized four Basque families and found evidence for linkage of autosomal dominant PD to the PARK8 locus, with a maximum 2-point logarithm of odds score of 3.21 (theta = 0.00) for marker D12S345. The clinical features of these families are those of typical PD, including good response to levodopa therapy, rigidity, and akinesia, and a mean age of 55 years at disease onset.
There is growing evidence in the scientific literature for shared risk and overlapping disease me... more There is growing evidence in the scientific literature for shared risk and overlapping disease mechanisms in the development of cancer and Parkinson disease (PD). This association has recently been highlighted with respect to melanoma and PD. Therefore, we review and discuss the literature concerning this unexplained link. A striking overlap is observed in the tyrosine and L-dopa biosynthetic pathways suggesting a common disease mechanism associated with these 2 heterogeneous disorders that warrants further investigation.
In 2004 it was first shown that mutations in LRRK2 can cause Parkinson's disease. This initia... more In 2004 it was first shown that mutations in LRRK2 can cause Parkinson's disease. This initial discovery was quickly followed by the observation that a single particular mutation is a relatively common cause of Parkinson's disease across varied populations. Further genetic investigation has revealed a variety of genetic ties to Parkinson's disease across this gene. These include common alleles with quite broad effects on risk, likely through both alterations at the protein sequence level, and in the context of expression. A great deal of functional characterization of LRRK2 and disease-causing mutations in this protein has occurred over the last 9 years, and considerable progress has been made. Particular attention has been paid to the kinase activity of LRRK2 as a therapeutic target, and while it is no means certain that this is viable target it is likely that this hypothesis will be tested in clinical trials sooner rather than later. We believe that the future goals fo...
In addition to the four well-confirmed genes linked to early-onset Parkinson disease (PD) (SNCA, ... more In addition to the four well-confirmed genes linked to early-onset Parkinson disease (PD) (SNCA, PARKIN, DJ-1, and PINK1), mutations in the leucine-rich repeat kinase 2 gene (LRRK2) have recently been identified in families with autosomal dominant late-onset PD. To perform mutation analysis of LRRK2 in probands of families showing dominant inheritance of PD and to conduct a case control association study to test the hypothesis that common coding variations might be associated with increased susceptibility to PD. All 51 LRRK2 coding exons were sequenced in 23 probands and the mutation frequencies were evaluated in 180 neurologically normal control subjects. For the association study the authors genotyped four coding LRRK2 polymorphisms in 250 normal control subjects and 121 patients with PD (predominantly white patients of Canadian origin), 84% of whom had age at onset before 50 years and 42% had a positive family history. The authors identified three probands with heterozygous LRRK2 mutations: two of them have the known G2019S substitution and one proband has a novel I1371V substitution. Mutation analysis of a large family demonstrated complete segregation of the G2019S with PD. However, there was no association between PD and any of the four polymorphisms at the allelic or genotypic levels (p > 0.17). Furthermore, the authors did not detect a modifying effect for any genotype or of APOE genotypes upon the age at onset in the PD group (p > 0.20). The results support the prior suggestion that LRRK2 mutations cause PD. The disease in the families reported here presents a phenotype indistinguishable from typical PD. All three families demonstrate a very variable age at onset that is not explained by APOE genotypes. The common coding variations in the LRRK2 gene neither constitute strong PD risk factors nor modify the age at onset; however, the possibility of a modest risk effect remains to be assessed in large datasets.
Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal domin... more Recently, mutations in LRRK2 encoding the protein dardarin have been linked to an autosomal dominant form of parkinsonism. To identify mutations causing Parkinson's disease (PD) in a cohort of North Americans with familial PD. We sequenced exons 1-51 of LRRK2 in 79 unrelated North American PD patients reporting a family history of the disease. One patient had a missense mutation (Thr2356Ile) while two others had the common Gly2019Ser mutation. In addition, 1 patient had a 4-bp deletion in close proximity to the exon 19 splice donor (IVS20+4delGTAA) that in vitro abrogates normal splicing. Our observations in the 79 North American patients indicate that mutations in LRRK2 are associated with approximately 5% of PD cases with a positive family history. The results also show that G2019S represents approximately half of the LRRK2 mutations in United States PD cases with a family history of the disease. We have identified two novel mutations in LRRK2.
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