Identification of UBAP1 mutations in juvenile hereditary spastic paraplegia in the 100,000 Genomes Project.

Hereditary spastic paraplegia (HSP) is a group of heterogeneous inherited degenerative disorders characterized by lower limb spasticity. Fifty percent of HSP patients remain yet genetically undiagnosed. The 100,000 Genomes Project (100KGP) is a large UK-wide initiative to provide genetic diagnosis to previously undiagnosed patients and families with rare conditions. Over 400 HSP families were recruited to the 100KGP. In order to obtain genetic diagnoses, gene-based burden testing was carried out for rare, predicted pathogenic variants using candidate variants from the Exomiser analysis of the genome sequencing data. A significant gene-disease association was identified for UBAP1 and HSP. Three protein truncating variants were identified in 13 patients from 7 families. All patients presented with juvenile form of pure HSP, with median age at onset 10 years, showing autosomal dominant inheritance or de novo occurrence. Additional clinical features included parkinsonism and learning difficulties, but their association with UBAP1 needs to be established

Aggregation-resistant alpha-synuclein tetramers are reduced in the blood of Parkinson's patients

Synucleinopathies such as Parkinson's disease (PD) are defined by the accumulation and aggregation of the α-synuclein protein in neurons, glia and other tissues. We have previously shown that destabilization of α-synuclein tetramers is associated with familial PD due to SNCA mutations and demonstrated brain-region specific alterations of α-synuclein multimers in sporadic PD patients following the classical Braak spreading theory. In this study, we assessed relative levels of disordered and higher-ordered multimeric forms of cytosolic α-synuclein in blood from familial PD with G51D mutations and sporadic PD patients. We used an adapted in vitro-cross-linking protocol for human EDTA-whole blood. The relative levels of higher-ordered α-synuclein tetramers were diminished in blood from familial PD and sporadic PD patients compared to controls. Interestingly, the relative amount of α-synuclein tetramers was already decreased in asymptomatic G51D carriers, supporting the hypothesis that α-synuclein multimer destabilization precedes the development of clinical PD. Our data, therefore suggest that measuring α-synuclein tetramers in blood may have potential as a facile biomarker assay for early detection and quantitative tracking of PD progression.</p

Prevalence of C9orf72 hexanucleotide repeat expansion in Greek patients with sporadic ALS

A total of 178 consecutive patients with definite sALS without frontotemporal dementia (FTD) were enrolled in this study, after complete clinical evaluation. A Repeat-Primed Polymerase Chain Reaction (RP-PCR) protocol was applied to detect the G4C2 repeats expansions. In the studied sALS patients, 5.06% (n = 9) carried the C9orf72 mutation. Among carriers, 2/3 of them were females and spinal onset accounted for 78% and bulbar for 22%, while the mean age of onset was about 60 years. Our study showed that the prevalence of C9orf72 repeat expansion in Greek sALS patients is similar to the overall frequency of the mutation in European populations. The pathogenic mutation remains a promising biomarker for genetic testing and targeted treatment.Fil: Sokratous, Maria. University Hospital Of Larissa; Grecia. University of Thessaly; GreciaFil: Schottlaender, Lucia Valentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Bourinaris, Thomas. UCL Queen Square Institute of Neurology; Reino UnidoFil: Marogianni, Chrysoula. University Hospital Of Larissa; Grecia. University of Thessaly; GreciaFil: Arnaoutoglou, Marianthi. Aristotle University Of Thessaloniki; GreciaFil: Patrikiou, Eleni. University of Thessaly; GreciaFil: Ralli, Styliani. University Hospital Of Larissa; Grecia. University of Thessaly; GreciaFil: Markou, Aikaterini. University Hospital Of Larissa; Grecia. University of Thessaly; GreciaFil: Dardiotis, Efthimios. University Hospital Of Larissa; Grecia. University of Thessaly; GreciaFil: Houlden, Henry. UCL Queen Square Institute of Neurology; Reino UnidoFil: Hadjigeorgiou, Georgios M.. University Hospital Of Larissa; Grecia. University of Thessaly; Grecia. University of Cyprus; ChipreFil: Xiromerisiou, Georgia. University Hospital Of Larissa; Grecia. University of Thessaly; Greci

Genotype-phenotype correlations and expansion of the molecular spectrum of AP4M1-related hereditary spastic paraplegia

Abstract Background Autosomal recessive hereditary spastic paraplegia (HSP) due to AP4M1 mutations is a very rare neurodevelopmental disorder reported for only a few patients. Methods We investigated a Greek HSP family using whole exome sequencing (WES). Results A novel AP4M1A frameshift insertion, and a very rare missense variant were identified in all three affected siblings in the compound heterozygous state (p.V174fs and p.C319R); the unaffected parents were carriers of only one variant. Patients were affected with a combination of: (a) febrile seizures with onset in the first year of life (followed by epileptic non-febrile seizures); (b) distinctive facial appearance (e.g., coarse features, bulbous nose and hypomimia); (c) developmental delay and intellectual disability; (d) early-onset spastic weakness of the lower limbs; and (e) cerebellar hypoplasia/atrophy on brain MRI. Conclusions We review genotype-phenotype correlations and discuss clinical overlaps between different AP4-related diseases. The AP4M1 belongs to a complex that mediates vesicle trafficking of glutamate receptors, being likely involved in brain development and neurotransmission

Additional file 1: FigureS1. of Genotype-phenotype correlations and expansion of the molecular spectrum of AP4M1-related hereditary spastic paraplegia

Expression of the AP4M1 gene in several regions of the human brain throughout development and aging. Note the higher expression levels during fetal development (birth is marked with a vertical solid line). Data from the Human Brain Transcriptome (HBT) project ( http://hbatlas.org ). CBC - cerebellar cortex, MD - mediodorsal nucleus of the thalamus, STR - striatum, AMY - amygdala, HIP - hippocampus, and NCX – neocortex. (PDF 68 kb

Expanding the Spectrum of AP5Z1-Related Hereditary Spastic Paraplegia (HSP-SPG48): A Multicenter Study on a Rare Disease.

Biallelic mutations in AP5Z1 are known to cause a rare, autosomal recessive, complex form of hereditary spastic paraplegia (HSP) referred to as SPG48 (MIM#613647)[1]. To date, only 11 SPG48 cases have been reported. The clinical spectrum of SPG48 is complex and heterogeneous, presenting with neuropathy, ataxia, dystonia and parkinsonism in addition to the spastic paraplegia (SP). AP5Z1 codes for the ζsubunit of the AP-5 complex, implicated in vesicular-mediated intracellular sorting and trafficking of cargo proteins[1] and functional studies demonstrate accumulation of multilamellar structures(endolysosomes) in SPG48 skin fibroblasts[2]

Defining the clinical, molecular and imaging spectrum of adaptor protein complex 4-associated hereditary spastic paraplegia

Abstract Bi-allelic loss-of-function variants in genes that encode subunits of the adaptor protein complex 4 (AP-4) lead to prototypical yet poorly understood forms of childhood-onset and complex hereditary spastic paraplegia: SPG47 (AP4B1), SPG50 (AP4M1), SPG51 (AP4E1) and SPG52 (AP4S1). Here, we report a detailed cross-sectional analysis of clinical, imaging and molecular data of 156 patients from 101 families. Enrolled patients were of diverse ethnic backgrounds and covered a wide age range (1.0–49.3 years). While the mean age at symptom onset was 0.8 ± 0.6 years [standard deviation (SD), range 0.2–5.0], the mean age at diagnosis was 10.2 ± 8.5 years (SD, range 0.1–46.3). We define a set of core features: early-onset developmental delay with delayed motor milestones and significant speech delay (50% non-verbal); intellectual disability in the moderate to severe range; mild hypotonia in infancy followed by spastic diplegia (mean age: 8.4 ± 5.1 years, SD) and later tetraplegia (mean age: 16.1 ± 9.8 years, SD); postnatal microcephaly (83%); foot deformities (69%); and epilepsy (66%) that is intractable in a subset. At last follow-up, 36% ambulated with assistance (mean age: 8.9 ± 6.4 years, SD) and 54% were wheelchair-dependent (mean age: 13.4 ± 9.8 years, SD). Episodes of stereotypic laughing, possibly consistent with a pseudobulbar affect, were found in 56% of patients. Key features on neuroimaging include a thin corpus callosum (90%), ventriculomegaly (65%) often with colpocephaly, and periventricular white-matter signal abnormalities (68%). Iron deposition and polymicrogyria were found in a subset of patients. AP4B1-associated SPG47 and AP4M1-associated SPG50 accounted for the majority of cases. About two-thirds of patients were born to consanguineous parents, and 82% carried homozygous variants. Over 70 unique variants were present, the majority of which are frameshift or nonsense mutations. To track disease progression across the age spectrum, we defined the relationship between disease severity as measured by several rating scales and disease duration. We found that the presence of epilepsy, which manifested before the age of 3 years in the majority of patients, was associated with worse motor outcomes. Exploring genotype-phenotype correlations, we found that disease severity and major phenotypes were equally distributed among the four subtypes, establishing that SPG47, SPG50, SPG51 and SPG52 share a common phenotype, an ‘AP-4 deficiency syndrome’. By delineating the core clinical, imaging, and molecular features of AP-4-associated hereditary spastic paraplegia across the age spectrum our results will facilitate early diagnosis, enable counselling and anticipatory guidance of affected families and help define endpoints for future interventional trials.</jats:p