Alterations in glutathione S-transferase pi expression following exposure to MPP+ -induced oxidative stress in the blood of Parkinson's disease patients

The major motor symptoms of Parkinson's disease do not occur until a majority of the dopaminergic neurons in the midbrain SNpc have already died. For this reason, it is critical to identify biomarkers that will allow for the identification of presymptomatic individuals. In this study, we examine the baseline expression of the anti-oxidant protein glutathione S-transferase pi (GSTpi) in the blood of PD patients and environmentally- and age-matched controls and compare it to GSTpi levels following exposure to 1-methyl-4-phenylpyridinium (MPP(+)), an agent that has been shown to induce oxidative stress. We find that after 4 h of exposure to MPP(+), significant increases in GSTpi levels can be observed in the leukocytes of PD patients. No changes were seen in other blood components. This suggests that GSTpi and potentially other members of this and other anti-oxidant families may be viable biomarkers for PD.

Wilson's disease

In the almost 100 years since Wilson's description of the illness that now bears his name, tremendous advances have been made in our understanding of this disorder. The genetic basis for Wilson's disease - mutation within the ATP7B gene - has been identified. The pathophysiologic basis for the damage resulting from the inability to excrete copper via the biliary system with its consequent gradual accumulation, first in the liver and ultimately in the brain and other organs and tissues, is now known. This has led to the development of effective diagnostic and treatment modalities that, although they may not eliminate the disorder, do provide the means for efficient diagnosis and effective amelioration if carried out in a dedicated and persistent fashion. Nevertheless, Wilson's disease remains both a diagnostic and treatment challenge for physician and patient. Its protean clinical manifestations make diagnosis difficult. Appropriate diagnostic evaluations to confirm the diagnosis and institute treatment can be confusing. In this chapter, the clinical manifestations, diagnostic evaluation, and treatment approaches for Wilson's disease are discussed.

A family with Parkinsonism, essential tremor, restless legs syndrome, and depression

BACKGROUND

Previous epidemiologic and genetic studies have suggested a link between Parkinson disease (PD), essential tremor (ET), and restless legs syndrome (RLS).

METHODS

We describe the clinical, PET, and pathologic characteristics of an extensive kindred from Arkansas with hereditary PD, ET, and RLS. The pedigree contains 138 individuals. Sixty-five family members were examined neurologically up to 3 times from 2004 to 2010. Clinical data were collected from medical records and questionnaires. Genetic studies were performed. Five family members underwent multitracer PET. Two individuals with PD were examined postmortem.

RESULTS

Eleven family members had PD with generally mild and slowly progressive symptoms. Age at onset was between 39 and 74 years (mean 59.1, SD 13.4). All individuals treated with l-dopa responded positively. Postural or action tremor was present in 6 individuals with PD, and in 19 additional family members. Fifteen persons reported symptoms of RLS. PET showed reduced presynaptic dopamine function typical of sporadic PD in a patient with PD and ET, but not in persons with ET or RLS. The inheritance pattern was autosomal dominant for PD and RLS. No known pathogenic mutation in PD-related genes was found. Fourteen of the family members with PD, ET, or RLS had depression. Neuropathologic examination revealed pallidonigral pigment spheroid degeneration with ubiquitin-positive axonal spheroids, TDP43-positive pathology in the basal ganglia, hippocampus, and brainstem, and only sparse Lewy bodies.

CONCLUSION

Familial forms of PD, ET, RLS, and depression occur in this family. The genetic cause remains to be elucidated.

The c.-237_236GA>TT THAP1 sequence variant does not increase risk for primary dystonia

BACKGROUND

Sequence variants in coding and noncoding regions of THAP1 have been associated with primary dystonia.

METHODS

In this study, 1,446 Caucasian subjects with mainly adult-onset primary dystonia and 1,520 controls were genotyped for a variant located in the 5'-untranslated region of THAP1 (c.-237_236GA>TT).

RESULTS

Minor allele frequencies were 62/2892 (2.14%) and 55/3040 (1.81%) in subjects with dystonia and controls, respectively (P=0.202). Subgroup analyses by gender and anatomical distribution also failed to attain statistical significance. In addition, there was no effect of the TT variant on expression levels of THAP1 transcript or protein.

DISCUSSION

Our findings indicate that the c.-237_236GA>TT THAP1 sequence variant does not increase risk for adult-onset primary dystonia in Caucasians.

Gastrointestinal dysfunction in Parkinson's disease

In recent years, an increasingly detailed picture of gastrointestinal dysfunction in the setting of Parkinson's disease has emerged. Abnormalities of function may occur at virtually all levels of the gastrointestinal tract. Weight loss, dental deterioration, salivary excess, dysphagia, gastroparesis, decreased bowel movement frequency, and anorectal dysfunction all may occur. The pathophysiologic basis for this dysfunction entails both central and enteric nervous system involvement.

Predictors of parkin mutations in early-onset Parkinson disease: the consortium on risk for early-onset Parkinson disease study

BACKGROUND

Mutations in the parkin gene are the most common genetic cause of early-onset Parkinson disease (PD). Results from a multicenter study of patients with PD systematically sampled by age at onset have not been reported to date.

OBJECTIVE

To determine risk factors associated with carrying parkin mutations.

DESIGN

Cross-sectional observational study.

SETTING

Thirteen movement disorders centers.

PARTICIPANTS

A total of 956 patients with early-onset PD, defined as age at onset younger than 51 years.

MAIN OUTCOME MEASURES

Presence of heterozygous, homozygous, or compound heterozygous parkin mutations.

RESULTS

Using a previously validated interview, 14.7% of patients reported a family history of PD in a first-degree relative. Sixty-four patients (6.7%) had parkin mutations (3.9% heterozygous, 0.6% homozygous, and 2.2% compound heterozygous). Copy number variation was present in 52.3% of mutation carriers (31.6% of heterozygous, 83.3% of homozygous, and 81.0% of compound heterozygous). Deletions in exons 3 and 4 and 255delA were common among Hispanics (specifically Puerto Ricans). Younger age at onset (<40 years) (odds ratio [OR], 5.0; 95% confidence interval [CI], 2.8-8.8; P = .001), Hispanic race/ethnicity (OR compared with white non-Hispanic race/ethnicity, 2.7; 95% CI, 1.3-5.7; P = .009), and family history of PD in a first-degree relative (OR compared with noncarriers, 2.8; 95% CI, 1.5-5.3; P = .002) were associated with carrying any parkin mutation (heterozygous, homozygous, or compound heterozygous). Hispanic race/ethnicity was associated with carrying a heterozygous mutation (OR compared with white non-Hispanic race/ethnicity, 2.8; 95% CI, 1.1-7.2; P = .03) after adjustment for covariates.

CONCLUSIONS

Age at onset, Hispanic race/ethnicity, and family history of PD are associated with carrying any parkin mutation (heterozygous, homozygous, or compound heterozygous) and heterozygous mutations alone. The increased odds of carrying a parkin mutation among Hispanics warrants further study.

Maternal inheritance and mitochondrial DNA variants in familial Parkinson's disease

Background

Mitochondrial function is impaired in Parkinson's disease (PD) and may contribute to the pathogenesis of PD, but the causes of mitochondrial impairment in PD are unknown. Mitochondrial dysfunction is recapitulated in cell lines expressing mitochondrial DNA (mtDNA) from PD patients, implicating mtDNA variants or mutations, though the role of mtDNA variants or mutations in PD risk remains unclear. We investigated the potential contribution of mtDNA variants or mutations to the risk of PD.

Methods

We examined the possibility of a maternal inheritance bias as well as the association between mitochondrial haplogroups and maternal inheritance and disease risk in a case-control study of 168 multiplex PD families in which the proband and one parent were diagnosed with PD. 2-tailed Fisher Exact Tests and McNemar's tests were used to compare allele frequencies, and a t-test to compare ages of onset.

Results

The frequency of affected mothers of the proband with PD (83/167, 49.4%) was not significantly different from the frequency of affected females of the proband generation (115/259, 44.4%) (Odds Ratio 1.22; 95%CI 0.83 - 1.81). After correcting for multiple tests, there were no significant differences in the frequencies of mitochondrial haplogroups or of the 10398G complex I gene polymorphism in PD patients compared to controls, and no significant associations with age of onset of PD. Mitochondrial haplogroup and 10398G polymorphism frequencies were similar in probands having an affected father as compared to probands having an affected mother.

Conclusions

These data fail to demonstrate a bias towards maternal inheritance in familial PD. Consistent with this, we find no association of common haplogroup-defining mtDNA variants or for the 10398G variant with the risk of PD. However, these data do not exclude a role for mtDNA variants in other populations, and it remains possible that other inherited mitochondrial DNA variants, or somatic mDNA mutations, contribute to the risk of familial PD.

Effects of moderate-volume, high-load lower-body resistance training on strength and function in persons with Parkinson's disease: a pilot study

Background. Resistance training research has demonstrated positive effects for persons with Parkinson's disease (PD), but the number of acute training variables that can be manipulated makes it difficult to determine the optimal resistance training program. Objective. The purpose of this investigation was to examine the effects of an 8-week resistance training intervention on strength and function in persons with PD. Methods. Eighteen men and women were randomized to training or standard care for the 8-week intervention. The training group performed 3 sets of 5–8 repetitions of the leg press, leg curl, and calf press twice weekly. Tests included leg press strength relative to body mass, timed up-and-go, six-minute walk, and Activities-specific Balance Confidence questionnaire. Results. There was a significant group-by-time effect for maximum leg press strength relative to body mass, with the training group significantly increasing their maximum relative strength (P < .05). No other significant interactions were noted (P > .05). Conclusions. Moderate volume, high-load weight training is effective for increasing lower-body strength in persons with PD.

Novel THAP1 sequence variants in primary dystonia

BACKGROUND

THAP1 encodes a transcription factor (THAP1) that harbors an atypical zinc finger domain and regulates cell proliferation. An exon 2 insertion/deletion frameshift mutation in THAP1 is responsible for DYT6 dystonia in Amish-Mennonites. Subsequent screening efforts in familial, mainly early-onset, primary dystonia identified additional THAP1 sequence variants in non-Amish subjects.

OBJECTIVE

To examine a large cohort of subjects with mainly adult-onset primary dystonia for sequence variants in THAP1.

METHODS

With high-resolution melting, all 3 THAP1 exons were screened for sequence variants in 1,114 subjects with mainly adult-onset primary dystonia, 96 with unclassified dystonia, and 600 controls (400 neurologically normal and 200 with Parkinson disease). In addition, all 3 THAP1 exons were sequenced in 200 subjects with dystonia and 200 neurologically normal controls.

RESULTS

Nine unique melting curves were found in 19 subjects from 16 families with primary dystonia and 1 control. Age at dystonia onset ranged from 8 to 69 years (mean 48 years). Sequencing identified 6 novel missense mutations in conserved regions of THAP1 (G9C [cervical, masticatory, arm], D17G [cervical], F132S [laryngeal], I149T [cervical and generalized], A166T [laryngeal], and Q187K [cervical]). One subject with blepharospasm and another with laryngeal dystonia harbored a c.-42C>T variant. A c.57C>T silent variant was found in 1 subject with segmental craniocervical dystonia. An intron 1 variant (c.71+9C>A) was present in 7 subjects with dystonia (7/1,210) but only 1 control (1/600).

CONCLUSIONS

A heterogeneous collection of THAP1 sequence variants is associated with varied anatomical distributions and onset ages of both familial and sporadic primary dystonia.

Neurologic presentations of gastrointestinal disease

In recent years, there has been increasing recognition of the presence of gastrointestinal (GI) dysfunction in the setting of neurologic diseases. Parkinson's disease is a particularly well-known example, but GI dysfunction also may occur in multiple sclerosis, stroke, and in various myopathic and peripheral neuropathic processes. There is much less awareness, however, that primary GI diseases may also display neurologic dysfunction as part of their clinical picture. This article focuses on some of those disease processes. Illnesses primarily targeting the GI tract are addressed and examples of primary esophageal, gastric, and intestinal disease processes are described.

Alpha-synuclein and familial Parkinson's disease

Whole gene duplications and triplications of alpha-synuclein (SNCA) can cause Parkinson's disease (PD), and variation in the promoter region (Rep1) and 3' region of SNCA has been reported to increase disease susceptibility. Within our cohort, one affected individual from each of 92 multiplex PD families showing the greatest evidence of linkage to the region around SNCA was screened for dosage alterations and sequence changes; no dosage or non-synonymous sequence changes were found. In addition, 737 individuals (from 450 multiplex PD families) that met strict diagnostic criteria for PD and did not harbor a known causative mutation, as well as 359 neurologically normal controls, were genotyped for the Rep1 polymorphism and four SNPs in the 3' region of SNCA. The four SNPs were in high LD (r(2) > 0.95) and were analyzed as a haplotype. The effects of the Rep1 genotype and the 3' haplotype were evaluated using regression models employing only one individual per family. Cases had a 3% higher frequency of the Rep1 263 bp allele compared with controls (OR = 1.54; empirical P-value = 0.02). There was an inverse linear relationship between the number of 263 bp alleles and age of onset (empirical P-value = 0.0004). The 3' haplotype was also associated with disease (OR = 1.29; empirical P-value = 0.01), but not age of onset (P = 0.40). These data suggest that dosage and sequence changes are a rare cause of PD, but variation in the promoter and 3' region of SNCA convey an increased risk for PD.

Parkin dosage mutations have greater pathogenicity in familial PD than simple sequence mutations

OBJECTIVE

Mutations in both alleles of parkin have been shown to result in Parkinson disease (PD). However, it is unclear whether haploinsufficiency (presence of a mutation in only 1 of the 2 parkin alleles) increases the risk for PD.

METHODS

We performed comprehensive dosage and sequence analysis of all 12 exons of parkin in a sample of 520 independent patients with familial PD and 263 controls. We evaluated whether presence of a single parkin mutation, either a sequence (point mutation or small insertion/deletion) or dosage (whole exon deletion or duplication) mutation, was found at increased frequency in cases as compared with controls. We then compared the clinical characteristics of cases with 0, 1, or 2 parkin mutations.

RESULTS

We identified 55 independent patients with PD with at least 1 parkin mutation and 9 controls with a single sequence mutation. Cases and controls had a similar frequency of single sequence mutations (3.1% vs 3.4%, p = 0.83); however, the cases had a significantly higher rate of dosage mutations (2.6% vs 0%, p = 0.009). Cases with a single dosage mutation were more likely to have an earlier age at onset (50% with onset at < or =45 years) compared with those with no parkin mutations (10%, p = 0.00002); this was not true for cases with only a single sequence mutation (25% with onset at < or =45 years, p = 0.06).

CONCLUSIONS

Parkin haploinsufficiency, specifically for a dosage mutation rather than a point mutation or small insertion/deletion, is a risk factor for familial PD and may be associated with earlier age at onset.

Impaired leg extensor strength in individuals with Parkinson disease and relatedness to functional mobility

Previous investigations have demonstrated leg strength deficits in persons with Parkinson's disease (PD) as compared to neurologically-normal adults. However, the exact mode of contraction by which strength is assessed may determine how closely such deficits are related to functional performance. The purpose of this study was to better understand the relationship of strength and functional mobility in persons with PD (n = 17, mean H&Y stage = 2.0) via comparison to a group of similar age healthy controls (n = 10) using a multi-joint isometric test of strength and various measures of functional mobility. Tests included isometric leg press maximum force relative to body mass, the Activities-specific Balance Confidence scale (ABC), postural sway under various unilateral stance and visual conditions, and the timed up and go (TUG). Relative force (p = 0.044) and ABC questionnaire mean scores (p < 0.001), showed controls performing better than PD subjects. The control group performed better than the PD group for length of path of the center of pressure except in the eyes closed positions (p < 0.05 for all). TUG time (p = 0.052) was not significantly different between the PD group and healthy controls. Leg press maximum force relative to body mass was however significantly correlated with TUG time (r = -0.68, p = 0.003) in persons with PD. There were no gender differences for any variables. These results suggest that some balance and functional mobility task performances are more worse for persons with mild-to-moderate PD than for neurologically-normal age-matched controls, which may be influenced by lessened lower extremity multi-joint strength. Strength training of the lower extremity utilizing such multi-joint actions may be beneficial for this population.

Variation in GIGYF2 is not associated with Parkinson disease

OBJECTIVE

A recent study reported that mutations in a gene on chromosome 2q36-37, GIGYF2, result in Parkinson disease (PD). We have previously reported linkage to this chromosomal region in a sample of multiplex PD families, with the strongest evidence of linkage obtained using the subset of the sample having the strongest family history of disease and meeting the strictest diagnostic criteria. We have tested whether mutations in GIGYF2 may account for the previously observed linkage finding.

METHODS

We sequenced the GIGYF2 coding region in 96 unrelated patients with PD used in our original study that contributed to the chromosome 2q36-37 linkage signal. Subsequently, we genotyped the entire sample of 566 multiplex PD kindreds as well as 1,447 controls to test whether variants in GIGYF2 are causative or increase susceptibility for PD.

RESULTS

We detected three novel variants as well as one of the previously reported seven variants in a total of five multiple PD families; however, there was no consistent evidence that these variants segregated with PD in these families. We also did not find a significant increase in risk for PD among those inheriting variants in GIGYF2 (p = 0.28).

CONCLUSIONS

We believe that variation in a gene other than GIGYF2 accounts for the previously reported linkage finding on chromosome 2q36-37.

High-throughput mutational analysis of TOR1A in primary dystonia

Background

Although the c.904_906delGAG mutation in Exon 5 of TOR1A typically manifests as early-onset generalized dystonia, DYT1 dystonia is genetically and clinically heterogeneous. Recently, another Exon 5 mutation (c.863G>A) has been associated with early-onset generalized dystonia and some ΔGAG mutation carriers present with late-onset focal dystonia. The aim of this study was to identify TOR1A Exon 5 mutations in a large cohort of subjects with mainly non-generalized primary dystonia.

Methods

High resolution melting (HRM) was used to examine the entire TOR1A Exon 5 coding sequence in 1014 subjects with primary dystonia (422 spasmodic dysphonia, 285 cervical dystonia, 67 blepharospasm, 41 writer's cramp, 16 oromandibular dystonia, 38 other primary focal dystonia, 112 segmental dystonia, 16 multifocal dystonia, and 17 generalized dystonia) and 250 controls (150 neurologically normal and 100 with other movement disorders). Diagnostic sensitivity and specificity were evaluated in an additional 8 subjects with known ΔGAG DYT1 dystonia and 88 subjects with ΔGAG-negative dystonia.

Results

HRM of TOR1A Exon 5 showed high (100%) diagnostic sensitivity and specificity. HRM was rapid and economical. HRM reliably differentiated the TOR1A ΔGAG and c.863G>A mutations. Melting curves were normal in 250/250 controls and 1012/1014 subjects with primary dystonia. The two subjects with shifted melting curves were found to harbor the classic ΔGAG deletion: 1) a non-Jewish Caucasian female with childhood-onset multifocal dystonia and 2) an Ashkenazi Jewish female with adolescent-onset spasmodic dysphonia.

Conclusion

First, HRM is an inexpensive, diagnostically sensitive and specific, high-throughput method for mutation discovery. Second, Exon 5 mutations in TOR1A are rarely associated with non-generalized primary dystonia.

Mutations in GBA are associated with familial Parkinson disease susceptibility and age at onset

OBJECTIVE

To characterize sequence variation within the glucocerebrosidase (GBA) gene in a select subset of our sample of patients with familial Parkinson disease (PD) and then to test in our full sample whether these sequence variants increased the risk for PD and were associated with an earlier onset of disease.

METHODS

We performed a comprehensive study of all GBA exons in one patient with PD from each of 96 PD families, selected based on the family-specific lod scores at the GBA locus. Identified GBA variants were subsequently screened in all 1325 PD cases from 566 multiplex PD families and in 359 controls.

RESULTS

Nine different GBA variants, five previously reported, were identified in 21 of the 96 PD cases sequenced. Screening for these variants in the full sample identified 161 variant carriers (12.2%) in 99 different PD families. An unbiased estimate of the frequency of the five previously reported GBA variants in the familial PD sample was 12.6% and in the control sample was 5.3% (odds ratio 2.6; 95% confidence interval 1.5-4.4). Presence of a GBA variant was associated with an earlier age at onset (p = 0.0001). On average, those patients carrying a GBA variant had onset with PD 6.04 years earlier than those without a GBA variant.

CONCLUSIONS

This study suggests that GBA is a susceptibility gene for familial Parkinson disease (PD) and patients with GBA variants have an earlier age at onset than patients with PD without GBA variants.