A Meta-Analysis of α-Synuclein Multiplication in Familial Parkinsonism

Chronic alpha-synuclein (SNCA) overexpression is a relatively homogenous and well-defined cause of parkinsonism and dementia. Parkinson's disease (PD), PD with dementia, dementia with Lewy bodies and multiple system atrophy all manifest in SNCA multiplication families. Herein we summarize genealogic, clinical and genetic data from 59 families (25 not previously published) with parkinsonism caused by SNCA multiplications. Longitudinal clinical assessments and genealogic relationships were documented for all family members. All probands were genotyped with an Illumina MEGA high-density genotyping array to identify copy number variants (CNV) and enable SNCA multiplication breakpoints to be defined. Three SNCA short tandem repeat (STR) markers were genotyped in all available samples to validate genomic dosage and inheritance. A web-application was built as a forum for future data sharing. CNV analysis identified 49 subjects with heterozygous SNCA duplication (CNV3), 2 with homozygous duplication (CNV4) and 7 with a triplication mutation (CNV4). Clinical presentations varied greatly throughout the cohort. SNCA dosage correlates with disease onset (mean age of onset CNV3: 46.9 ± 10.5 years vs. 34.5 ± 7.4 CNV4, p = 0.003). Atypical or more severe clinical courses were described in several patients and dementia was noted in 50.9% of the probands. Neither the multiplication size (average 2.05 ± 2.45 Mb) nor the number of genes included (range 1–50) was associated with motor symptom onset or dementia. Families with SNCA multiplication are rare and globally-distributed. Nevertheless, they may both inform and benefit from the development of SNCA targeted therapeutic strategies relevant to the treatment of all alpha-synucleinopathies

Schizophrenia miR-137 Locus Risk Genotype is Associated with DLPFC Hyperactivation

MiR-137 dysregulation has been implicated in the etiology of schizophrenia, but its functional role remains to be determined

Diagnostic Yield and Treatment Impact of Targeted Exome Sequencing in Early-Onset Epilepsy

Targeted whole-exome sequencing (WES) is a powerful diagnostic tool for a broad spectrum of heterogeneous neurological disorders. Here, we aim to examine the impact on diagnosis, treatment and cost with early use of targeted WES in early-onset epilepsy. WES was performed on 180 patients with early-onset epilepsy (≤5 years) of unknown cause. Patients were classified as Retrospective (epilepsy diagnosis >6 months) or Prospective (epilepsy diagnosis <6 months). WES was performed on an Ion Proton™ and variant reporting was restricted to the sequences of 620 known epilepsy genes. Diagnostic yield and time to diagnosis were calculated. An analysis of cost and impact on treatment was also performed. A molecular diagnoses (pathogenic/likely pathogenic variants) was achieved in 59/180 patients (33%). Clinical management changed following WES findings in 23 of 59 diagnosed patients (39%) or 13% of all patients. A possible diagnosis was identified in 21 additional patients (12%) for whom supporting evidence is pending. Time from epilepsy onset to a genetic diagnosis was faster when WES was performed early in the diagnostic process (mean: 145 days Prospective vs. 2,882 days Retrospective). Costs of prior negative tests averaged $8,344 per patient in the Retrospective group, suggesting savings of$5,110 per patient using WES. These results highlight the diagnostic yield, clinical utility and potential cost-effectiveness of using targeted WES early in the diagnostic workup of patients with unexplained early-onset epilepsy. The costs and clinical benefits are likely to continue to improve. Advances in precision medicine and further studies regarding impact on long-term clinical outcome will be important

Case reports: novel TUBG1 mutations with milder neurodevelopmental presentations

Background: Tubulinopathies result from mutations in tubulin genes, including TUBG1, responsible for cell microtubules, are characterized by brain development abnormalities, microcephaly, early-onset epilepsy, and motor impairment. Only eleven patients with TUBG1 mutations have been previously described in literature to our knowledge. Here we present two new patients with novel de novo TUBG1 mutations and review other cases in the literature. Case presentations: Both patients have microcephaly and intellectual disability. Patient B further fits a more typical presentation, with well-controlled epilepsy and mild hypertonia, whereas Patient A’s presentation is much milder without these other features. Conclusion: This report expands the spectrum of TUBG1 mutation manifestations, suggesting the possibility of less severe phenotypes for patients and families, and influencing genetic counselling strategies.Medicine, Faculty ofOther UBCReviewedFacult

p.Met233Val in a Complex Neurodegenerative Movement and Neuropsychiatric Disorder

Mutations in presenilin 1 (PSEN1) are the most common cause of autosomal dominant Alzheimer’s disease. Here, we report a Canadian-Vietnamese family carrying a PSEN1 p.Met233Val mutation with an exceptionally early and severe presentation that includes a wide range of atypical symptoms, including prominent ataxia, Parkinsonism, spasticity, dystonia, action tremor, myoclonus, bulbar symptoms, seizures, hallucinations and behavioral changes. Whole-exome sequencing (WES) was performed on the affected proband after many assessments over several years proved diagnostically inconclusive. The results were analyzed using the AnnEx “Annotated Exomes” browser (http://annex.can.ubc.ca), a web-based platform that facilitates WES variant annotation and interpretation. High-throughput sequencing can be especially informative for complex neurological disorders, and WES warrants consideration as a first-line clinical test. Data analyses facilitated by web-based bioinformatics tools have great potential for novel insight, although confirmatory, diagnostically accredited Sanger sequencing is recommended prior to reporting

Identification of the first alu-mediated large deletion involving the f5 gene in a compound heterozygous patient with severe factor v deficiency

Factor V (FV) deficiency is a rare autosomal recessive haemorrhagic disorder associated with moderate to severe bleeding symptoms. Conventional mutational screening leads to a complete molecular genetic diagnosis only in about 80-90% of cases. Large gene rearrangements, which could explain at least part of the "missing alleles" have not been reported so far in FV-deficient patients. In this work, we investigated a family with hereditary FV deficiency, in which the proband is compound heterozygous for a 205-Kb deletion, involving the first seven exons of F5, and the entire selectin P, L, and E genes, and for a novel splicing mutation (IVS12+5G>A). The deletion breakpoints, determined by using a combination of semi-quantitative real-time PCR and long PCR assays, occurred within AluY repeat sequences, suggesting an Alu-mediated unequal homologous recombination as the mechanism responsible for the deletion. The in vitro characterisation of the IVS12+5G>A mutation demonstrated that this mutation causes the skipping of exon 12 and the activation of a cryptic splice site. Low levels of residual wild-type splicing were also detectable, in agreement with the notion that the complete absence of FV may be not compatible with life. \ua9 Schattauer 2011

Common variants in the haemostatic gene pathway contribute to risk of early-onset myocardial infarction in the Italian population

Occlusive coronary thrombus formation superimposed on an atherosclerotic plaque is the ultimate event leading to myocardial infarction (MI). Therefore, haemostatic proteins may represent important players in the pathogenesis of MI. It was the objective of this study to evaluate, in a comprehensive way, the role of haemostatic gene polymorphisms in predisposition to premature MI. A total of 810 single nucleotide polymorphisms (SNPs) in 37 genes were assessed for association with MI in a large cohort (1,670 males, 210 females) of Italian patients who suffered from an MI event before the age of 45, and an equal number of controls. Thirly-eight SNPs selected from the literature were genotyped using the SNPlex technology, whereas genotypes for the remaining 772 SNPs were extracted from a previous genome-wide association study. Genotypes were analysed by a standard case-control analysis corrected for classical cardiovascular risk factors, and by haplotype analysis. A weighted Genetic Risk Score (GRS) was calculated. Evidence for association with MI after covariate correction was found for 35 SNPs in 12 loci: F5, PROS1, F11, ITGA2, F12, F13A1, SERPINE1, PLAT, VWF, THBD, PROCR, and F9. The weighted GRS was constructed by including the top SNP for each of the 12 associated loci. The GRS distribution was significantly different between cases and controls, and subjects in the highest quintile had a 2.69-fold increased risk for MI compared with those in the lowest quintile. Our results suggest that a GRS, based on the combined effect of several risk alleles in different haemostatic genes, is associated with an increased risk of MI