[Mutations in sarcomeric genes MYH7, MYBPC3, TNNT2, TNNI3, and TPM1 in patients with hypertrophic cardiomyopathy]

INTRODUCTION AND OBJECTIVES

Mutation of a sarcomeric gene is the most frequent cause of hypertrophic cardiomyopathy. For each such gene, however, previous studies have reported a range of different mutation frequencies, and clinical manifestations have been highly heterogeneous, both of which limit the use of genetic information in clinical practice. Our aim was to determine the frequency of mutations in the sarcomeric genes MYH7, MYBPC3, TNNT2, TNNI3, and TPM1 in a cohort of Spanish patients with hypertrophic cardiomyopathy.

METHODS

We used sequencing to analyze the coding regions of these five genes in 120 patients (29% with a family history) and investigated how the patient phenotype varied with the gene mutated.

RESULTS

In total, 32 patients were found to have mutations: 10 in MYH7 (8%), 20 in MYBPC3 (16%), 2 in TNNT2, 1 in TPM1 and none in TNNI3. Overall, 61% of mutations had not been described before. Two patients had two mutations (i.e., double mutants). There was no difference in the mean age at diagnosis or the extent of the hypertrophy between those with MYH7 mutations and those with MYBPC3 mutations.

CONCLUSIONS

Some 26% of patients had a mutation in one of the five sarcomeric genes investigated. More than half of the mutations had not been described before. The MYBPC3 gene was the most frequently mutated, followed by MYH7. No phenotypic differences were observed between carriers of the various mutations, which makes it difficult to use genetic information to stratify risk in these patients.

First case of highly pathogenic H5N1 avian influenza virus in Spain

Background

The H5N1 strain of avian influenza virus has been involved in severe mortality in domestic poultry, and has also been found in different species of wildlife in Europe. The Basque Country avian influenza surveillance program began sample collection and processing the fall of 2005.

Results

Here we report the first confirmation of the presence of highly pathogenic H5N1 strain in a Great Crested Grebe (Podiceps cristatus) found dead in a pond near Vitoria in the Basque Country on the North of Spain. Regarding the survey for generic influenza type A virus, we have obtained positive results in about 8% of more that 3500 birds examined.

Conclusion

We think that the self-limiting nature of our finding and others proves that certain regions have ecological, geographical and climatological features that make it difficult for the H5N1 virus to spread [1] and cause disease at least in the large scale scenario that has been worrying human and animal health authorities during the last years.

Mutational screening of the mitochondrial transcription factors B1 and B2 (TFB1M and TFB2M) in Parkinson's disease

Mitochondrial dysfunction has been implicated in Parkinson's disease (PD). The nuclear encoded transcription factors A, B1 and B2 are essential for mitochondrial DNA replication. Sequence variants at the genes encoding TFAM, TFB1M and TFB2M could contribute to the risk of developing PD. Here, we searched for TFB1M and TFB2M nucleotide variants in a cohort of PD-patients (n=300) and healthy controls (n=200) from Spain. Single strand conformation analysis and direct sequencing were used to determine the variation at all the coding exons of the two genes. In addition to previously reported polymorphisms, we found several rare variants in patients and controls. Allele frequencies for all the nucleotide changes did not differ between patients and controls. Our work suggests that DNA variants in TFB1M and TFB2M did not contribute to the risk for PD in our population.

[Pasteurella multocida bacteremic meningitis]

Human infections by Pasteurella multocida are usually associated with bites or scratches from dogs and cats. Many of them are accompanied by other oropharyngeal microorganisms of these animals. We herein present a case of bacteremic meningitis by P. multocida in an 86-year-old woman who was living with seven cats. Even though no skin or soft tissue infection was recorded, it is possible that a mild infection had gone undetected and a subsequent bacteremia had impacted on the meninges, or that meningitis could have occurred after nasopharyngeal colonization (not demonstrated). The isolates obtained from blood cultures and cerebrospinal fluid were identified as P. multocida by API 20NE, API 20E, and Vitek 1. In agreement with findings in the literature, this strain was susceptible to penicillin, cefotaxime, levofloxacin and tetracyclines.

Mitochondrial transcription factor A (TFAM) gene variation and risk of late-onset Alzheimer's disease

Impaired mitochondrial function and an increased number of mutations in mitochondrial DNA (mtDNA) has been found in brains of patients with late-onset Alzheimer's disease (LOAD). The TFAM-gene encodes the mitochondrial transcription factor A, a protein that controls the transcription, replication, damage sensing, and repair of mtDNA. TFAM is on human chromosome region 10q21.1, where a locus for LOAD has been mapped. Our objective was to determine the role of TFAM-gene variation in the risk of LOAD. The seven TFAM coding exons were analysed through single strand conformation analysis and direct sequencing in a cohort of Spanish LOAD-patients and healthy controls. We found four common polymorphisms, two in the flanquing intronic and two in the coding sequences. Polymorphism rs1937 (+35 G/C) was the only missense change (S12T). Genotyping of this polymorphism in 300 LOAD-patients and 183 healthy controls showed a significantly higher frequency of GG-homozygotes in the patients (92% vs. 86%; p=0.04; OR=1.91, 95%CI=1.02-3.50). This suggests that S12 is a risk factor for LOAD in our population. In conclusion, rare variants (mutations) in the TFAM gene were not found in LOAD-patients, but the S12T polymorphism was a moderate risk factor for LOAD in our population.

A search for cyclophilin-A gene variants in cyclosporine A-treated renal transplanted patients

BACKGROUND

The cyclophilin A (CypA)-cyclosporine (CsA) complex promotes immune response. The variation at the CypA gene could explain CsA-pharmacokinetics and clinical outcomes among CsA-treated patients.

METHODS

The study included 290 kidney transplanted patients (65% male; mean age 51 +/- 15 yr), treated with CsA. The five CypA- exons and the promoter region were analysed through single-strand conformation analysis, denaturing high performance liquid chromatography, and direct sequencing. The effect of a promoter polymorphism (-11 G/C) on gene expression was analysed in cell-cultures.

RESULTS

We found two polymorphisms in the promoter (-11 G/C) and exon 1 (+36 G/A). Genotype frequencies did not differ between patients according to their pharmacokinetics status. In vitro studies showed that -11 G/C affected gene expression. The -11 G allele was significantly associated with clinical nephrotoxicity (p = 0.006). The strongest predictors for nephrotoxicity were a donor age > or =55 yr, and the promoter GG + GC genotypes.

CONCLUSIONS

Our work suggests that a CypA-promoter polymorphism (-11 G/C) could be associated with clinical nephrotoxicity. Replication of this study in other populations is necessary to define the role of CypA-variants in the main clinical outcomes among CsA-treated kidney-transplanted patients.

Association between the Stin2 VNTR polymorphism of the serotonin transporter gene and treatment outcome in alcohol-dependent patients

AIMS

The aim of this study was to investigate the potential association between functional polymorphisms of dopaminergic [dopamine receptor D2 (DRD2), dopamine receptor D3 (DRD3) and dopamine transporter (SLC6A3)] and serotonergic [serotonin 2A receptor (HTR2A) and serotonin transporter (SLC6A4)] genes and treatment outcome in alcohol-dependent patients.

METHODS

A total of 90 Spanish Caucasian alcohol-dependent outpatients (ICD-10 criteria) were enrolled in the study. The association between genotypes and drinking outcomes was measured over 6 months of treatment. Biomarkers of alcohol consumption, as well as alcohol consumption and its consequences, craving, disability and quality of life, were assessed. Based on those measures, we created a composite secondary measure to globally assess treatment outcome in alcoholism.

RESULTS

No association was found between DRD2, DRD3, SLC6A3 or HTR2A gene variants and treatment outcome. However, SLC6A4 STin2 12/12 carriers showed poor 6-month time point treatment outcome [32.8% in the good outcome group versus 64.0% in the poor outcome group, chi(2) (df) = 7.20 (1), corrected P = 0.042, OR (95% CI) = 0.27 (0.10-0.72)]. Nevertheless, independent analysis of each treatment group reveals that the excess of 12/12 carriers in the poor outcome group was only found in the naltrexone-treated group [24.1% versus 64.7% chi(2) (df) = 7.41 (1), corrected P = 0.042, OR (95% CI) = 0.17 (0.05-0.64)]. In the whole sample, the L-10 repeats haplotype (5-HTTLPR-STin2 VNTR) is associated with good outcome (LRT = 3.88, df = 1, P = 0.049).

CONCLUSIONS

Our findings suggest that functional polymorphism of the SLC6A4 gene may have an influence on treatment outcome in alcohol-dependent patients.

Association study between obsessive-compulsive disorder and serotonergic candidate genes

BACKGROUND

To date, research examining the relationship between serotonergic genes and obsessive-compulsive disorder (OCD) has yielded conflicting results. The purpose of this study is to investigate the association between four serotonergic polymorphisms (STin2 VNTR and 5-HTTLPR of the SLC6A4 gene, and A-1438G (rs6311) and T102C (rs6313) of the HTR2A gene) and OCD.

METHODS

99 OCD patients, 456 non-OCD psychiatric patients, and 420 healthy controls from a homogeneous Spanish Caucasian population were genotyped using standard methods.

RESULTS

All groups showed Hardy-Weinberg equilibrium for the analyzed genetic variability. A-1438G and T102C polymorphisms were in complete linkage disequilibrium. OCD patients showed an excess of STin2.12 carriers (12/12, 12/10, and 12/9 genotypes) compared with healthy controls (chi(2) (1)=7.21, corrected p=0.021; OR=3.38, 95% CI=1.32-8.62) and non-OCD psychiatric patients (chi(2) (1)=6.70, corrected p=0.030; OR=3.24, 95% CI=1.27-8.26). However, no differences were found between non-OCD patients and healthy controls (chi(2) (1)=0.05, corrected p>1; OR=1.04, 95% CI=0.72-1.51). No significant differences were found with respect to A-1438G and 5-HTTLPR polymorphisms.

CONCLUSIONS

Our data provide supporting evidence of an association between the STin2 VNTR polymorphism of the SLC6A4 gene and OCD.

[Clinical aspects and endoscopic management of gastrointestinal bleeding from Dieulafoy's lesion]

OBJECTIVE

the aim of the study was to assess the incidence, clinical presentation, location, and response to endoscopic therapy of gastrointestinal bleeding from Dieulafoy's lesion.

MATERIAL AND METHOD

ALL consecutive episodes of gastrointestinal bleeding due to Dieulafoy's lesion seen between 2000 and 2006 were retrospectively reviewed. All main clinical and endoscopic data were collected: type and effectiveness of endoscopic therapy, rebleeding, complications, and mortality during hospitalization.

RESULTS

WE found 41 patients, 26 males and 15 females, median age of 71.19 years. Dieulafoy's lesion accounted for 1.55% of all gastrointestinal bleeding episodes during the study period. The incidence of Dieulafoy's lesion was 2.2 cases/100.000 inhabitants/year. Active bleeding at endoscopy was present in 85.36%, and comorbidity in 92.68%. The stomach was the most frequent location (60.97%), followed by duodenum (29.26%). Endoscopic therapy achieved initial hemostasis in all cases. Three patients (7.31%) initially treated with epinephrine injection showed rebleeding and properly responded to a second session of endoscopic therapy. No surgery was needed. The mortality rate during hospitalization was 4.87%.

CONCLUSIONS

Dieulafoy's lesion is an uncommon, but potentially severe cause of gastrointestinal bleeding. It may be found in any location within the gastrointestinal tract. Endoscopic therapy is effective and safe. Injected epinephrine alone is associated with a higher risk of rebleeding.

Association between heroin dependence and 5-HT2A receptor gene polymorphisms

OBJECTIVE

To investigate the association between four polymorphisms of the 5-HT(2A) receptor and 5-HT transporter genes and heroin dependence.

METHODS

113 heroin- dependent patients (DSM-IV criteria) and 420 unrelated healthy controls from Asturias (Northern Spain) were genotyped using standard methods.

RESULTS

There was an apparent difference in the distribution of genotypes for A-1438G polymorphisms (p = 0.024, not significant after Bonferroni correction). The 5-HT(2A) -1438A allele was significantly more common in patients than controls [0.55 and 0.45, respectively; corrected p = 0.042, OR = 1.51 (95% CI = 1.13-2.03)]. An interaction was observed between A-1438G of 5-HT(2A) and 5-HTT polymorphisms. The association between the -1438AA vs. AG/GG genotypes and heroin dependence was enhanced in the presence of 12-repeat 5-HTT VNTR and short 5-HTTLPR alleles [24.8% in heroin-dependent patients vs. 12.6% in controls; corrected p = 0.045, OR = 2.28 (95% CI = 1.36-3.82)].

CONCLUSIONS

Our findings support a contribution of the 5-HT(2A) gene to susceptibility to heroin dependence, as well as a possible synergistic effect of 5-HT(2A) and 5-HTT genes on susceptibility to heroin dependence.

Mitochondrial haplogroup T is negatively associated with the status of elite endurance athlete

Mitochondrial function is absolutely necessary to supply the energy required for muscles, and germ line mutations in mitochondrial genes have been related with impaired cardiac function and exercise intolerance. In addition, alleles at several polymorphic sites in mtDNA define nine common haplogroups, and some of these haplogroups have been implicated in the risk of developing several diseases. In this study, we analysed the association between mtHaplogroups and the capacity to reach the status of elite endurance athlete. DNA was obtained from blood leukocytes of 95 Spanish elite endurance athletes and 250 healthy male population controls. We analysed eight mitochondrial polymorphisms and the frequencies were statistically compared between elite athletes and controls. Haplogroup T, specifically defined by 13368A, was significantly less frequent among elite endurance athletes (p =0.012, Fisher's exact test). Our study suggests that allele 13368A and mitochondrial haplogroup T might be a marker negatively associated with the status of elite endurance athlete. This mitochondrial variant could be related with a lower capacity to respond to endurance training, through unknown mechanisms involving a less efficient mitochondrial workload.

Prevalence and spectrum of mutations in the sarcomeric troponin T and I genes in a cohort of Spanish cardiac hypertrophy patients

We sequenced the coding exons of the cardiac troponins T (TNNT2) and I (TNNI3) genes in 115 Spanish HCM-patients (32% with a family history of the disease). Only two (2%) had mutations in the TNNT2 (Arg278>Cys and Arg92>Lys). These mutations were associated with variable clinical outcomes. No patient had TNNI3-mutation. We also genotyped these patients and 320 healthy controls for a 5 bp insertion/deletion (I/D) polymorphism in intron 3 of TNNT2. DD-homozygotes for the 5 bp I/D polymorphism were significantly more frequent among the patients (OR=1.83, 95% CI=2.10-5.16).

Pseudoachalasia of the cardia secondary to nongastrointestinal neoplasia

A minor proportion of patients with achalasia eventually have a neoplasm and, as a consequence, pseudoachalasia is diagnosed. A neoplasm may either involve gastrointestinal junction or present a paraneoplastic effect. Over the global diagnoses of achalasia issued in 5 years of experience in our motility unit, we have found 13% (3/23 cases) of pseudoachalasia (2-4% in previous series, probably due to the fact that the population assisted was mainly composed of elderly patients). The origin of the neoplasm was bladder, prostate and metastases from epidermoid carcinoma of vocal chord. Treatment of primary neoplasm, besides classical approach (with dilatation of botulinum injection) may help in the resolution of this clinical disorder.

Radial endoscopic ultrasonography and buried bumper endoscopic solution

Percutaneous endoscopic gastrostomy is a widely used technique for long-term enteral nutrition. Buried bumper syndrome is one of the long-term complications of percutaneous endoscopic gastrostomy, and occurs when the internal retention bolster ulcerates the gastric mucosa, migrates into the deeper gastric wall and becomes covered by gastric mucosa. Clinically, this migration is revealed by a gradual increase of resistance at feeding administration and during catheter cleaning. It can also cause the infection of the site, leading to inflammatory changes and even sepsis. We show an endoscopic solution with argon beam local gastric destruction plus Savary dilatator introduction in the gastric camera. Endoscopic ultrasonography previous visualization of the gastric wall let's to realize this endoscopic solution.

Lack of association between endothelial nitric oxide synthase (NOS3) gene polymorphisms and suicide attempts

OBJECTIVE

The aim of this study is to investigate the association between two polymorphisms of endothelial nitric oxide synthase (NOS3) and suicide attempts.

METHODS

We genotyped 186 suicide attempters and 420 unrelated healthy controls. The following polymorphisms were analysed: T-786C and 27-bp repeat in intron 4.

RESULTS

No significant differences were found in genotype or in allelic distribution of the aforesaid polymorphisms. There were also no differences in the genotype distribution or allelic frequencies when separately assessing males and females or impulsive and non-impulsive attempters and normal controls. Estimated haplotype frequencies were similar in both groups.

CONCLUSION

Our data do not support the hypothesis that genetically determined changes in the NOS3 gene confer increased susceptibility for suicidal behavior.

Association study of serotonin 2A receptor (5-HT2A) and serotonin transporter (5-HTT) gene polymorphisms with schizophrenia

OBJECTIVE

To investigate (i) the association between four serotonergic polymorphisms (A-1438G and T102C of the 5-HT2A receptor gene, and 5-HTT VNTR and 5-HTTLPR of the 5-HT transporter gene) and schizophrenia and (ii) the potential interaction of those polymorphisms in the development of schizophrenia.

SUBJECTS AND METHODS

227 outpatients with schizophrenia (DSM-IV criteria) and 420 unrelated healthy controls from Asturias (Northern Spain) were genotyped using standard methods.

RESULTS

Both groups showed Hardy-Weinberg equilibrium for the analyzed genetic variability. A-1438G and T102C polymorphisms are in complete linkage disequilibrium in our population. There was an apparent difference in the distribution of genotypes for the A-1438G (or T102C) polymorphisms (p=0.018, not significant after a Bonferroni correction). The 5-HT2A -1438A (or 102T) allele was significantly more frequent in patients than controls (0.53 and 0.45, respectively; corrected p=0.028, OR=1.39 (95% CI=1.11-1.75)). Genotype and allele distributions for 5-HTT polymorphisms were similar in both groups. However, assessment of the combined influence of 5-HT2A A-1438G and 5-HTTLPR polymorphisms demonstrated a significant effect (chi(2) (3)=11.51, p=0.009), whereby the combination of -1438A and 5-HTTLPR S alleles was associated with schizophrenia.

CONCLUSIONS

Our findings support a possible synergistic effect of genetic factors influencing serotonergic neurotransmission on susceptibility to schizophrenia.

Role of the CDKN1A/p21, CDKN1C/p57, and CDKN2A/p16 genes in the risk of atherosclerosis and myocardial infarction

Atherosclerosis is characterized by excessive proliferation of neointimal leukocytes and vascular smooth muscle cells (VSMCs). In mice, the manipulation of cell cycle inhibitors such as CDKN1B (p27) and CDKN1A (p21) modifies the risk of developing atherosclerosis. In humans, CDKN1A, CDKN1B and CDKN1C (p57) are differentially expressed in normal versus atherosclerotic vessels. A DNA-polymorphism within the CDKN1B promoter has been associated with myocardial infarction (MI). In the present study, we analyzed the effect of CDKN1A, CDKN1C and CDKN2A (p16) polymorphisms on MI-risk. A total of 316 patients (all male, < 55 years) and 434 controls were genotyped, and the allele and genotype frequencies were compared between the two groups. Two CDKN1C polymorphisms, a promoter GT-repeat and a variable number of repeats of the amino acid PAPA-motif, were associated with MI. The presence of two alleles < or = 11-repeats (9/11, 10/11 and 11/11 genotypes) was significantly less frequent among patients (p < 0.001). This difference was also significant when analyzing the subpopulation of smokers (p = 0.004), suggesting a protective role for these low-repeat genotypes (OR = 0.49, 95%CI = 0.32-0.73). The PAPA-BB homozygotes were significantly less frequent in patients, but this could be attributed to a linkage disequilibrium between the 11-repeats and B alleles. No significantly different frequencies between patients and controls for the four CDKN1A (-1026A/G, -754G/C, -369G/C and Ser31Arg) and the three CDKN2A (-523 G/A, +22 G/A and Ala148Thr) polymorphisms was found. In conclusion, we provide here genetic evidence for the association between DNA-variants in the CDKN1C/p57 gene and the risk of atherosclerosis and MI.

Screening of the endothelin1 gene (EDN1) in a cohort of patients with essential left ventricular hypertrophy

Our objective was to analyse the role of endothelin1 gene (EDN1) variation in essential left ventricular hypertrophy (LVH). We searched for EDN1 variants in 145 Spanish patients with an essential form of LVH (not secondary to hypertension, aortic stenosis, or any other disease that could explain the hypertrophy). The five EDN1 coding exons and 1.5 kilobases of the promoter region were analysed through single strand conformation analysis and direct sequencing. We found four nucleotide changes: -1224 C/A (promoter), -131 ins/del A (exon 1, 5'-non-translated sequence), A/G in codon 106 (exon 3, silent), and G/T in codon 198 (exon 5, lys198asn). To determine the association between these polymorphisms and cardiac hypertrophy, we compared the genotype frequencies from these 145 patients with 250 healthy controls. We found a higher frequency of patients homozygous for 198 lys (198 KK) (65% vs. 52%; p = 0.01; OR = 1.76) and for -1224 AA (73% vs. 66%; p = 0.19). Homozygotes for -1224 A + 198 K (AA+KK) were significantly more frequent in patients (62% vs. 45%; p = 0.0007; OR = 2.10; 95% CI = 1.35-3.25). The expression of the -1224 C/A and exon 5 K198N variants was analysed with cells in culture. These in vitro studies showed that these variations did not differ in their expression levels. In conclusion, our work has shown that EDN1 variation, and in particular homozygosity for the -1224A/198K haplotype, is associated with the risk of developing cardiac hypertrophy. However, these EDN1 variants do not affect in vitro gene expression.

No association between Parkinson's disease and three polymorphisms in the eNOS, nNOS, and iNOS genes

Nitric oxide synthases (NOS) and mitochondrial DNA-polymorphisms have been associated with the risk of developing Parkinson's disease (PD). In this report, we genotyped 450 PD-patients and 200 controls for three polymorphisms in the endothelial, inducible and neuronal NOS-genes, and for the T4336C and A10398G mitochondrial DNA-polymorphisms. None of the eNOS (intron 4 VNTR), iNOS (exon 22 A/G), or nNOS (exon 29T/C) were significantly associated with PD. Mitochondrial 4336C increased the PD-risk among women (OR=6.13), while the 10398G had a protective effect (OR=0.52). We did not find significantly interactions between the NOS and mitochondrial polymorphisms in the risk for PD in our population.

Vesicoureteric reflux and tumor necrosis factor-alpha gene polymorphism

AIM

To determine the role of tumor necrosis factor-alpha (TNF-alpha) gene polymorphism in promoting renal scarring among patients with vesicoureteric reflux (VUR). This genetic variant involves a guanosine to adenine transition at position -308, and this single-base polymorphism is associated with increased transcription of the TNF-alpha gene. Recent studies suggest that the TNF-alpha gene may be associated with predisposition to renal scarring.

PATIENTS AND METHODS

A total of 195 (51.8% females) patients with VUR demonstrated by voiding cystourethrogram were recruited, 126 of them with reflux nephropathy diagnosed by dimercaptosuccinic scan. The control group included 266 healthy individuals. Genotyping was performed by polymerase chain reaction and digestion with a restriction enzyme.

RESULTS

Allele frequencies of -308G and -308A were 83.8% and 16.2%, respectively in patients with VUR and 88.9% and 11.1%, respectively in controls (P<0.05). No differences were found in genotype distribution related to presence/absence of renal scars. There was no relationship between TNF-alpha genotype and grade of VUR or the presence of proteinuria.

CONCLUSIONS

Our data suggest that the TNF-alpha AA genotype is not associated with reflux nephropathy. The TNF-alpha-308A allele could be related to a higher susceptibility to VUR.

Digenic parkinsonism: investigation of the synergistic effects of PRKN and LRRK2

The complex genetic etiology of Parkinson's disease (PD) is indicative of a multifactorial syndrome. A combination of gene-gene and gene-environment interactions may determine a variable phenotypic outcome. Recently a direct gene/protein interaction between two of the most common genetic causes of parkinsonism PRKN and LRRK2 has been postulated. We have identified three Spanish patients simultaneously harboring mutations in PRKN and LRRK2. In comparison to other Spanish patients with a single LRRK2 or PRKN mutation, the three double-mutation patients reported here do not present with an earlier age-at-onset or a faster progression of disease. Although the clinical findings do not support a synergistic effect of LRRK2 and PRKN, a potential genetic interplay might be concealed by the modulating effects of other genes. Nevertheless, this work demonstrates that the presence of mutations in one familial gene should not serve as exclusion criteria in a screen for further genetic variation. Direct interaction of Lrrk2 and parkin proteins was not observed in co-immunoprecipitation pull down experiments. However, in vivo studies are required to assess whether there is an indirect link between Lrrk2 and parkin in disease pathogenesis.