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Objective: Recessive variants in the PINK1 gene are known causes of early-onset Parkinson's disease (EOPD). To describe the clinical features and genetic profiles of patients with PINK1-related Parkinson's disease (PARK-PINK1) mutations., Methods: We conducted a retrospective chart review of the demographic, clinical and genetic details of patients from our database carrying biallelic PINK1 variants., Results: A total of 7 patients whose median age at onset was 33 years (range: 20-49) were recruited. All had asymmetrical onset, tremors were present in 4 patients, abnormal posturing was present in 2 patients, and slowness was present in 1 patient. The parkinsonism phenotype was noted in 6 patients (with dystonia in four) and isolated dystonia in one. Among the 6 patients with parkinsonism, five had rest tremors, all had good levodopa responses, and four had motor fluctuations with choreiform dyskinesia. Exome sequencing revealed biallelic pathogenic/likely pathogenic variants, five of which were novel., Conclusion: PARK-PINK1 presents as an EOPD with tremor-predominant phenotype, good levodopa-responsiveness, early motor fluctuation and dyskinesia. We describe five novel variants in PINK1 gene.

Between 3–5% of all patients with Parkinson’s disease (PD) have onset before the age of 40 years, which is likely related to genetic causes. Parkin gene mutations are the most common mutations, which are associated with autosomal recessive early-onset PD. A 34-year-old Emirati female presented with complaints of limb and speech tremor. She had been having difficulties in initiating movement and speech during her job. These problems began two years ago and had become progressively worsened. Her medical history was significant for generalized seizures for the past three years, which was well controlled with prescription medications. She was unaware of any family members with Parkinson’s or any genetic disorders. Her examination revealed a reduction in eyelid blinking movement and hypomimia facial appearance. She had severe bilateral upper and lower extremity rigidity, which was more evident on her right side. While resting, the patient exhibited bilateral pin-rolling tremors in both of her upper extremities. Her gait was shuffling in nature with reduced arm swing and abnormal retropulsion. All of her laboratory investigations were normal. Genetic analysis revealed a homozygous 1 base pair insertion in exon 5 of PARK2 gene (c.601_602insA), resulting in a nonsense mutation causing a stop codon instead of a cysteine codon (p. Cys201X). The patient showed an excellent response to treatment. We described a case of early-onset PD in a female, who on genetic analysis, was found to have a previously undescribed homozygous mutation in the PARK2 gene.

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder. The neuropathological hallmark of the disease is the loss of dopamine neurons of the substantia nigra pars compacta. The clinical manifestations of PD are bradykinesia, rigidity, resting tremors and postural instability. PD patients often display non-motor symptoms such as depression, anxiety, weakness, sleep disturbances and cognitive disorders. Although, in 90% of cases, PD has a sporadic onset of unknown etiology, highly penetrant rare genetic mutations in many genes have been linked with typical familial PD. Understanding the mechanisms behind the DA neuron death in these Mendelian forms may help to illuminate the pathogenesis of DA neuron degeneration in the more common forms of PD. A key step in the identification of the molecular pathways underlying DA neuron death, and in the development of therapeutic strategies, is the creation and characterization of animal models that faithfully recapitulate the human disease. In this review, we outline the current status of PD modeling using mouse, rat and non-mammalian models, focusing on animal models for autosomal recessive PD.

OBJECTIVE: Genetic studies for Parkinson’s disease (PD) which have been increased during last few years have shown that parkin (PARK2), DJ-1 (PARK7) and PINK-1 (PARK6) mutations can cause autosomal recessive early-onset parkinsonism. OBJECTIVE: The aim of this study was to investigate by genetic screening methods, the presence of possible genetic mutations in two siblings who have developed PD. METHODS: In these two brothers, PD started at the age of 48 with cervical dystonia and bradykinesia on the left arm, and 56 with tremor on the right hand, respectively. Although they had a favorable response to levodopa, they developed wearing-off phenomenon without dyskinesia on the 4th year. Besides dystonia, the younger brother experienced psychosis and impulse control disorder, as well. Family history revealed first degree consanguinity and the father had also a diagnosis of PD. PD progressed rather slowly in both, but unfortunately the older brother died due to lung cancer 10 years after the initial diagnosis of PD, while he was on the stage 2 of Hoehn-Yahr scale. The younger brother is still on our follow-up at the 7th year of his PD. Informed consent was obtained and blood samples were sent to the genetic department of Juntendo University in Japan for genetic analysis. Parkin gene mutation and DJ-1 gene mutation were analyzed on the PARK7 locus, by automated direct nucleotide sequencing and performed gene dosage assay using TaqMan real-time quantitive PCR. RESULTS: After excluding the parkin mutation the presence of PARK7 was detected in both siblings with haplotype analysis. DJ-1 gene mutation analysis responsible for PARK7, revealed a deletion on intron 1. CONCLUSION: A rarely encountered PARK7 mutation was identified in two brothers having slowly progressive PD and a favorable response to levodopa, one of whom also had psychotic symptoms. As in the presented cases, the genetic studies performed on early-onset PD patients with positive family history provide significant contributions to the sub-group identification of the disease which exhibits clinical heterogeneity

Background Recessive mutations in the PTEN-induced putative kinase 1 ( PINK1 ) gene cause early-onset Parkinson's disease (EOPD). The clinical phenotype of families that have this PINK1 -associated disease may present with different symptoms, including typical PD. The loss of the PINK1 protein may lead to mitochondrial dysfunction, which causes dopaminergic neuron death. Methods The clinical phenotypes of a large Polish family with EOPD and an identified PINK1 homozygous nonsense mutation were assessed. Ubiquitination and degradation of mitochondrial parkin substrates as well as mitochondrial bioenergetics were investigated as direct functional readouts for PINK1's kinase activity in biopsied dermal fibroblasts. Results A four-generation family was genealogically evaluated. Genetic screening identified two affected subjects who were both homozygous carriers of the pathogenic PINK1 p.Q456X substitution. Both patients presented with dystonia and gait disorders at symptom onset. Seven heterozygous mutation carriers remained unaffected. Functional studies revealed that the PINK1 p.Q456X protein is non-functional in activating the downstream ubiquitin ligase parkin and priming the ubiquitination of its substrates, and that the RNA levels of PINK1 were significantly reduced. Conclusions The PINK1 p.Q456X mutation leads to a decrease in mRNA and a loss of protein function. The foot dystonia and gait disorders seen at disease onset in affected members of our family, which were accompanied by parkinsonism had a similar clinical presentation to what has been described in previous reports of PINK1 mutation carriers. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aimed to elucidate the genetic causes underlying early-onset Parkinsonism ( EOP) in a consanguineous Iranian family. To attain this, homozygosity mapping and whole-exome sequencing were performed. As a result, a homozygous mutation (c.773G>A; p.Arg258Gln) lying within the NH2-terminal Sac1-like inositol phosphatase domain of polyphosphoinositide phosphatase synaptojanin 1 ( SYNJ1), which has been implicated in the regulation of endocytic traffic at synapses, was identified as the disease-segregating mutation. This mutation impaired the phosphatase activity of SYNJ1 against its Sac1 domain substrates in vitro. We concluded that the SYNJ1 mutation identified here is responsible for the EOP phenotype seen in our patients probably due to deficiencies in its phosphatase activity and consequent impairment of its synaptic functions. Our finding not only opens new avenues of investigation in the synaptic dysfunction mechanisms associated with Parkinsonism, but also suggests phosphoinositide metabolism as a novel therapeutic target for Parkinsonism. [ABSTRACT FROM AUTHOR]

Mutations in the DJ-1 gene lead to autosomal recessive early-onset parkinsonism. We performed F-DOPA and FDG PET neuroimaging in two parkinsonism patients homozygous for DJ-1 mutations, three relatives heterozygous for a DJ-1 mutation and one non-carrier, all from the originally described kindred from The Netherlands. Their characteristics were compared to those of typical Parkinson’s disease patients and healthy controls. Both parkinsonism patients had reduced F-DOPA uptake concordant with typical Parkinson’s disease. In the, clinically unaffected, heterozygous relatives, F-DOPA metabolism was unremarkable, thus not suggesting a dosage effect of the DJ-1 gene. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is the most common neurodegenerative movement disorder. The neuropathological hallmark of the disease is the loss of dopamine neurons of the substantia nigra pars compacta. The clinical manifestations of PD are bradykinesia, rigidity, resting tremors and postural instability. PD patients often display non-motor symptoms such as depression, anxiety, weakness, sleep disturbances and cognitive disorders. Although, in 90% of cases, PD has a sporadic onset of unknown etiology, highly penetrant rare genetic mutations in many genes have been linked with typical familial PD. Understanding the mechanisms behind the DA neuron death in these Mendelian forms may help to illuminate the pathogenesis of DA neuron degeneration in the more common forms of PD. A key step in the identification of the molecular pathways underlying DA neuron death, and in the development of therapeutic strategies, is the creation and characterization of animal models that faithfully recapitulate the human disease. In this review, we outline the current status of PD modeling using mouse, rat and non-mammalian models, focusing on animal models for autosomal recessive PD. [ABSTRACT FROM AUTHOR]

Abstract: DJ-1 mutations cause autosomal recessive parkinsonism (ARP). Although some reports of DJ-1 mutations have been published, there is lack of information on the prevalence of these mutations in large-scale studies of both familial and sporadic parkinsonism. In this genetic screening study, we analyzed the distribution and frequency of DJ-1 mutations by direct nucleotide sequencing of coding exons and exon–intron boundaries of DJ-1, in 386 parkin-negative parkinsonism patients (371 index cases: 67 probands of autosomal recessive parkinsonism families, 90 probands of autosomal dominant parkinsonism families, 201 patients with sporadic parkinsonism, and 13 with unknown family histories) from 12 countries (Japan 283, China 27, Taiwan 22, Korea 22, Israel 16, Turkey 5, Philippines 2, Bulgaria 2, Greece 2, Tunisia 1, USA 2, Ukraine 1, unknown 1). None had causative mutation in DJ-1, suggesting DJ-1 mutation is very rare among patients with familial and sporadic parkinsonism from Asian countries and those with other ethnic background. This is in contrast to the higher frequencies and worldwide distribution of parkin- and PINK1-related parkinsonism in ARP and sporadic parkinsonism. Thus, after obtaining clinical information, screening for mutations in (1) parkin, (2) PINK1, (3) DJ-1, (4) ATP13A2 should be conducted in that order, in ARP and sporadic parkinsonism, based on their reported frequencies. In addition, haplotype analysis should be employed to check for homozygosity of 1p36, which harbors a cluster of causative genes for ARP such as DJ-1, PINK1 and ATP13A2 in ARP and sporadic parkinsonism, especially in parkinsonism with consanguinity. [Copyright &y& Elsevier]