Ana Djarmati

DJ-1 (PARK7) mutations are less frequent than Parkin (PARK2) mutations in early-onset Parkinson disease

Background: Mutations in the Parkin gene (PARK2) are the most commonly identified cause of recessively inherited early-onset Parkinson disease (EOPD) but account for only a portion of cases. DJ-1 (PARK7) was recently reported as a second gene associated with recessively inherited PD with a homozygous exon deletion and a homozygous point mutation in two families. Methods: To investigate the frequency of DJ-1 mutations, the authors performed mutational analysis of all six coding exons of DJ-1 in 100 EOPD patients. For the detection of exon rearrangements, the authors developed a quantitative duplex PCR assay. Denaturing high performance liquid chromatography analysis was used to screen for point mutations and small deletions. Further, Parkin analysis was performed as previously described. Results: The authors identified two carriers of single heterozygous loss-of-function DJ-1 mutations, including a heterozygous deletion of exons 5 to 7 and an 11-base pair deletion, removing the invariant donor splice site in intron 5. Interestingly, both DJ-1 mutations identified in this study were found in the heterozygous state only. The authors also detected a polymorphism (R98Q) in 1.5% of the chromosomes in both the patient and control group. In the same patient sample, 17 cases were detected with mutations in the Parkin gene. Conclusions: Mutations in DJ-1 are less frequent than mutations in Parkin in EOPD patients but should be considered as a possible cause of EOPD. The effect of single heterozygous mutations in DJ-1 on the nigrostriatal system, as described for heterozygous changes in Parkin and PARK6, remains to be elucidated.

PINK1 , Parkin , and DJ-1 mutations in Italian patients with early-onset parkinsonism

Recessively inherited early-onset parkinsonism (EOP) has been associated with mutations in the Parkin, DJ-1, and PINK1 genes. We studied the prevalence of mutations in all three genes in 65 Italian patients (mean age of onset: 43.2±5.4 years, 62 sporadic, three familial), selected by age at onset equal or younger than 51 years. Clinical features were compatible with idiopathic Parkinsons disease in all cases. To detect small sequence alterations in Parkin, DJ-1, and PINK1, we performed a conventional mutational analysis (SSCP/dHPLC/sequencing) of all coding exons of these genes. To test for the presence of exon rearrangements in PINK1, we established a new quantitative duplex PCR assay. Gene dosage alterations in Parkin and DJ-1 were excluded using previously reported protocols. Five patients (8%; one woman/four men; mean age at onset: 38.2±9.7 (range 25–49) years) carried mutations in one of the genes studied: three cases had novel PINK1 mutations, one of which occurred twice (homozygous c.1602_1603insCAA; heterozygous c.1602_1603insCAA; heterozygous c.836G>A), and two patients had known Parkin mutations (heterozygous c.734A>T and c.924C>T; heterozygous c.924C>T). Family history was negative for all mutation carriers, but one with a history of tremor. Additionally, we detected one novel polymorphism (c.344A>T) and four novel PINK1 changes of unknown pathogenic significance (−21G/A; IVS1+97A/G; IVS3+38_40delTTT; c.852C>T), but no exon rearrangements. No mutations were found in the DJ-1 gene. The number of mutation carriers in both the Parkin and the PINK1 gene in our cohort is low but comparable, suggesting that PINK1 has to be considered in EOP.

Recessively Inherited Parkinsonism: Effect of ATP13A2 Mutations on the Clinical and Neuroimaging Phenotype

OBJECTIVE To determine clinical features and to identify changes in brain structure and function in compound heterozygous and heterozygous ATP13A2 mutation carriers. DESIGN Prospective multimodal clinical and neuroimaging study. SETTING University of Lübeck, Lübeck, Germany. PARTICIPANTS Eight family members of a large Chilean pedigree with Kufor-Rakeb syndrome (KRS). INTERVENTIONS Clinical characterization, dopamine transporter (DAT) imaging, voxel-based morphometry (VBM), and transcranial sonography (TCS). MAIN OUTCOME MEASURES Frequency of parkinsonian signs, brain structure, and functional alterations. RESULTS The only available patient with compound heterozygous KRS showed a markedly reduced striatal DAT density bilaterally. Magnetic resonance imaging revealed severe global brain atrophy as well as iron deposition in the basal ganglia. The heterozygous mother had definite parkinsonism with reduced DAT density in both putamina. While all asymptomatic heterozygous siblings displayed subtle extrapyramidal signs, DAT imaging revealed striatal tracer uptake within physiological levels. Voxel-based morphometry revealed an increase in gray matter volume in the right putamen and a decrease in the cerebellum of the heterozygous carriers. In all mutation carriers, the substantia nigra had a normal appearance on TCS. CONCLUSIONS Single ATP13A2 heterozygous mutations may be associated with clinical signs of parkinsonism and contribute to structural and functional brain changes. Lack of hyperechogenicity in the substantia nigra may be a distinctive feature of this form of genetic parkinsonism. This, along with the finding of iron in the basal ganglia in our patient with KRS, implies a different underlying pathophysiology compared with other monogenic forms of parkinsonism and idiopathic PD and may place KRS among the syndromes of neurodegeneration with brain iron accumulation (NBIA).

Transcranial sonography findings in a large family with homozygous and heterozygous PINK1 mutations

Objective: To investigate substantia nigra (SN) echogenicity in members of a family with homozygous and heterozygous PTEN induced kinase (PINK1) mutations with or without signs of Parkinson’s disease (PD). Methods: Transcranial sonography (TCS) was used to investigate 20 members of a family with PINK1 mutations, including four homozygous and 11 heterozygous mutation carriers and five individuals with no mutation. For comparison, a healthy control group of 18 subjects without a positive family history of PD (control group) and a healthy control group of 15 subjects with a positive family history of sporadic PD (relative group) were investigated. For statistical analysis, the larger area of the two SNs echogenicity (aSNmax) of each individual was selected. Results: A significantly increased aSNmax was found for all subgroups compared with the control group. The group of homozygous carriers of a PINK1 mutation had a significantly increased aSNmax compared with all of the other subgroups, except the group of heterozygous mutation carriers. Conclusions: These findings in carriers of a PINK1 mutation are comparable with those in carriers of Parkin mutations and non-genetic PD. The increased aSNmax in family members without a mutation suggests an additional contributing factor independent of the PINK1 mutation that may also play a role in relatives of patients with sporadic PD.

Co-occurrence of affective and schizophrenia spectrum disorders with PINK1 mutations

Objective: To investigate a possible association of mutations in the PTEN-induced putative kinase 1 (PINK1) gene with psychiatric disorders in a large family with monogenic parkinsonism. Method: 20 members of a family (4 homozygous, 11 heterozygous and 5 non-mutation carriers) were investigated for the presence of psychiatric disorders using the structured clinical interview for Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV); information on three additional heterozygous mutation carriers was obtained according to the family history research diagnostic criteria. Results: We found predominantly affective and schizophrenia spectrum disorders in 11 (61%) of the 18 mutation carriers and in 1 (20%) of the 5 mutation-negative cases. Conclusions: First, affective and psychotic symptoms may be part of the phenotypic spectrum or even the sole manifestation of PINK1 mutations. Second, patients with familial movement disorders associated with psychiatric conditions may serve as a valuable study population to explore (genetic) causes of neuropsychiatric disease.

ATP13A2 variants in early-onset Parkinson's disease patients and controls.

Four genes responsible for recessively inherited forms of Parkinsons disease (PD) have been identified, including the recently discovered ATP13A2 (PARK9) gene. Our objective was to investigate the role of this gene in a large cohort of PD patients and controls. We extensively screened all 29 exons of the ATP13A2 coding region in 112 patients with early‐onset PD (EOPD; <40 years) of mostly European ethnic origin and of 55 controls. We identified four carriers (3.6%) of novel single heterozygous ATP13A2 missense changes that were absent in controls. Interestingly, the carrier of one of these variants also harbored two mutations in the Parkin gene. None of the carriers had atypical features previously described in patients with two mutated ATP13A2 alleles (Kufor–Rakeb syndrome). Our data suggest that two mutated ATP13A2 alleles are not a common cause of PD. Although heterozygous variants are present in a considerable number of patients, they are—based on this relatively small sample—not significantly more frequent in patients compared to controls.

A large-scale genetic association study to evaluate the contribution of Omi/HtrA2 (PARK13) to Parkinson's disease.

High-profile studies have provided conflicting results regarding the involvement of the Omi/HtrA2 gene in Parkinsons disease (PD) susceptibility. Therefore, we performed a large-scale analysis of the association of common Omi/HtrA2 variants in the Genetic Epidemiology of Parkinsons disease (GEO-PD) consortium. GEO-PD sites provided clinical and genetic data including affection status, gender, ethnicity, age at study, age at examination (all subjects); age at onset and family history of PD (patients). Genotyping was performed for the five most informative SNPs spanning the Omi/HtrA2 gene in approximately 2-3 kb intervals (rs10779958, rs2231250, rs72470544, rs1183739, rs2241028). Fixed as well as random effect models were used to provide summary risk estimates of Omi/HtrA2 variants. The 20 GEO-PD sites provided data for 6378 cases and 8880 controls. No overall significant associations for the five Omi/HtrA2 SNPs and PD were observed using either fixed effect or random effect models. The summary odds ratios ranged between 0.98 and 1.08 and the estimates of between-study heterogeneity were not large (non-significant Q statistics for all 5 SNPs; I(2) estimates 0-28%). Trends for association were seen for participants of Scandinavian descent for rs2241028 (OR 1.41, p=0.04) and for rs1183739 for age at examination (cut-off 65 years; OR 1.17, p=0.02), but these would not be significant after adjusting for multiple comparisons and their Bayes factors were only modest. This largest association study performed to define the role of any gene in the pathogenesis of Parkinsons disease revealed no overall strong association of Omi/HtrA2 variants with PD in populations worldwide.

A heterozygous frameshift mutation in PRKRA (DYT16) associated with generalised dystonia in a German patient

We have read with great interest the article in The Lancet Neurology by Camargos and colleagues who describe the fi nding of DYT16 dystonia, a novel, recessively inherited form of early-onset generalised dystonia that is associated with a missense mutation in the gene that encodes PPKRA. The homozygous mutation was found in seven aff ected members from three Brazilian families. In one family, the mother of a homozygous carrier was also aff ected but could not be genotyped. This raises the question of whether a heterozygous mutation might act as a susceptibility factor for dystonia. A similar scenario has been discussed for seemingly recessive genes that are linked to parkinsonism. To explore further the role of mutations in PRKRA, we screened patients with dystonia and controls for changes in the sequence of this gene. The phenotypic spectrum associated with mutations in PRKRA is, for the most part, unknown; on the basis of early onset (<25 years; mean 13·7 [SD 7·4] years), a positive family history (n=9), and limb involvement, we identifi ed 52 unrelated patients with dystonia: 22 patients presented with generalised dystonia, 11 with segmental dystonia, 15 with musician’s dystonia, and four with writer’s cramp. By use of published primer sequences, we sequenced all the coding exons and fl anking intronic sequences of PRKRA in these patients. The known and newly detected sequence variations were tested in a further 75 patients with dystonia (mean age of onset of 31·6 [6·4] years), of whom 15 had a positive family history of dystonia, and in 189 neurologically healthy controls (mean age: 57·7 [11·6] years). We identifi ed a novel heterozygous mutation (c.266_267delAT; p.H89fsX20) in exon 3 of PRKRA in patient 14741 (fi gure). This predicted frameshift mutation, which might cause premature truncation of the protein, was absent in the other patients and the controls. We did not detect any other mutations in PRKRA in this patient. Clinically, he presented with early-childhood-onset leg dystonia that spread gradually over the course of a few years. His family history was unremarkable for any movement disorder; secondary causes of dystonia were excluded; and brain MRI was normal. At his last examination, the patient, C C G

Evidence for linkage of restless legs syndrome to chromosome 9p Are there two distinct loci

Background: Restless legs syndrome (RLS) is a common sensory-motor disorder characterized by paresthesias and an intense urge to move the legs with a considerable familial aggregation. To date, no gene mutation has been found, but five gene loci have been mapped in primary RLS to chromosomes 12q, 14q, 9p, 2q, and 20p (RLS1 through 5). Patients/Methods: We identified a four-generational German RLS family with 37 family members including 15 affected cases. We performed linkage analysis using microsatellite markers at the five known loci. Prompted by the identification of a potentially shared haplotype near the RLS3 locus, we expanded the investigated linkage region on chromosome 9p using additional DNA markers. Results: Mode of inheritance in our RLS family was compatible with an autosomal dominant pattern, and disease onset was mainly in childhood or adolescence. We excluded linkage to the RLS1, RLS2, RLS4, and RLS5 loci. However, we identified a likely new RLS gene locus (RLS3*) on chromosome 9p with a maximum lod score of 3.60 generated by model-based multipoint linkage analysis. A haplotype flanked by D9S974 and D9S1118 in a 9.9-Mb region, centromeric to RLS3, was shared by all 12 investigated patients. In addition, 11 of them carried a common haplotype extending telomeric to D9S2189 that is located within RLS3. Conclusions: We demonstrate linkage to a locus on chromosome 9p that is probably distinct from RLS3. Our family with a rather homogeneous phenotype and very early disease onset represents a unique opportunity to further elucidate the genetic causes of the frequent restless leg syndrome.

Co‐occurrence of restless legs syndrome and Parkin mutations in two families

Recent studies have suggested an association between restless legs syndrome (RLS) and Parkinsons disease (PD). We present a large multigenerational family and a smaller family with RLS. A Parkin mutation was found in 10 of 20 patients from both families with idiopathic RLS but was not considered causative. The clinical phenotype did not differ between RLS patients with and without a Parkin mutation. Inheritance of RLS was consistent with autosomal dominant transmission, and linkage analysis excluded all three known loci for RLS.