ABSTRACT: The HipSci project brings together diverse constituents in genomics, proteomics, cell biology and clinical genetics to create a UK national iPS cell resource and use it to carry out cellular genetic studies. In this sub-study we performed Genotyping analysis using the Infinium HumanExome BeadChip on iPS cells generated from skin biopsies or blood samples from rare disease patients diagnosed with Hereditary Spastic Paraplegia.
Project description:Hereditary spastic paraplegias are a group of genetically heterogeneous neurological disorders characterized by progressive weakness and spasticity of lower limbs. We ascertained five families with eight individuals with hereditary spastic paraplegia. Pathogenic variants were identified by exome sequencing of index cases. The cohort consists of three families with spastic paraplegia type 47 (AP4B1) with a common mutation in two families, a family with spastic paraplegia type 50 (AP4M1), and two male siblings with X-linked spastic paraplegia 2 (PLP1). This work illustrates locus and allelic heterogeneity in five families with hereditary spastic paraplegia.
Project description:BACKGROUND:Autosomal recessive hereditary spastic paraplegia (ARHSP) with thin corpus callosum (TCC) is a common form of complex hereditary spastic paraplegia. The genetic lesion underlying ARHSP-TCC was localized to chromosome 15q13-q15 and given the designation SPG11. Recently, the gene encoding spatacsin (KIAA1840) has been shown to contain mutations that underlie the majority of ARHSP-TCC cases. METHODS:We present a complete analysis of the 40 coding exons of this gene in patients with sporadic (n = 25) or familial (20 probands) complex hereditary spastic paraplegia with and without thinning of the corpus callosum. RESULTS:We identified seven mutations, including deletions, insertions, and nonsense mutations, which were all predicted to lead to premature truncation of the protein. CONCLUSION:We conclude that mutations on KIAA1840 are frequent in complex autosomal recessive hereditary spastic paraplegia but an infrequent cause of sporadic complex hereditary spastic paraplegia.
Project description:The goal of this project is to study differentially expressed genes in patients affected by Hereditary Spastic Paraplegia (HSP) linked to mutations of the gene encoding spastin an ubiquitously expressed protein that has recently been shown to be involved in microtubule regulation and vesicle trafficking by cell culture studies. Gene profiling was done with Affymetrix U95Av2 GeneChips using the total RNA extracted from muscle biopsies of 3 SPG4-linked HSP patients.
Project description:We have identified a missense mutation in the motor domain of the neuronal kinesin heavy chain gene KIF5A, in a family with hereditary spastic paraplegia. The mutation occurs in the family in which the SPG10 locus was originally identified, at an invariant asparagine residue that, when mutated in orthologous kinesin heavy chain motor proteins, prevents stimulation of the motor ATPase by microtubule-binding. Mutation of kinesin orthologues in various species leads to phenotypes resembling hereditary spastic paraplegia. The conventional kinesin motor powers intracellular movement of membranous organelles and other macromolecular cargo from the neuronal cell body to the distal tip of the axon. This finding suggests that the underlying pathology of SPG10 and possibly of other forms of hereditary spastic paraplegia may involve perturbation of neuronal anterograde (or retrograde) axoplasmic flow, leading to axonal degeneration, especially in the longest axons of the central nervous system.
Project description:Homozygous mutations in MAG, encoding the myelin-associated glycoprotein, a transmembrane component of the myelin sheath, have been associated with SPG 75 recessive spastic paraplegia. Here, we report the first patient with two compound heterozygous novel MAG mutations (p.A151V and p.S373R) and early developmental delay with a progressive complex phenotype characterized by spastic paraplegia, peripheral sensorimotor neuropathy, intellectual disability, and sensorial dysfunctions with severe optic atrophy and hearing involvement. Brain imaging showed progressive global cerebellar atrophy. We propose that complex hereditary spastic paraplegia, with axonal and demyelinating polyneuropathy, sensorial impairment and intellectual disability might suggest MAG mutations.
Project description:Background:Autosomal recessive hereditary spastic paraplegias (HSP) are a rare group of hereditary neurodegenerative disorders characterized by spasticity with or without other symptoms. SPG11 gene is the most common cause of autosomal recessive HSP. We report a case of autosomal recessive spastic paraplegia type 76 due to heterozygous variants of CAPN1 in an Argentinean subject. Case Presentation:A 38-year-old Argentinean female presented with progressive gait problems and instability of 15-year duration. Oculomotor abnormalities, ataxia, bradykinesia, cervical dystonia, and lower limb pyramidal signs were observed. Brain MRI was unremarkable. Whole-exome sequencing analysis identified two heterozygous variants in CAPN1. Conclusions:Clinicians should screen for CAPN1 mutation in a young female patient without significant family history with a spastic paraplegia syndrome associated with other symptoms.
Project description:Variants in the KIF1A gene can cause autosomal recessive spastic paraplegia 30, autosomal recessive hereditary sensory neuropathy, or autosomal (de novo) dominant mental retardation type 9. More recently, variants in KIF1A have also been described in a few cases with autosomal dominant spastic paraplegia. Here, we describe 20 KIF1A variants in 24 patients from a clinical exome sequencing cohort of 347 individuals with a mostly 'pure' spastic paraplegia. In these patients, spastic paraplegia was slowly progressive and mostly pure, but with a highly variable disease onset (0-57 years). Segregation analyses showed a de novo occurrence in seven cases, and a dominant inheritance pattern in 11 families. The motor domain of KIF1A is a hotspot for disease causing variants in autosomal dominant spastic paraplegia, similar to mental retardation type 9 and recessive spastic paraplegia type 30. However, unlike these allelic disorders, dominant spastic paraplegia was also caused by loss-of-function variants outside this domain in six families. Finally, three missense variants were outside the motor domain and need further characterization. In conclusion, KIF1A variants are a frequent cause of autosomal dominant spastic paraplegia in our cohort (6-7%). The identification of KIF1A loss-of-function variants suggests haploinsufficiency as a possible mechanism in autosomal dominant spastic paraplegia.
Project description:The hereditary spastic paraplegias are a heterogeneous group of degenerative disorders that are clinically classified as either pure with predominant lower limb spasticity, or complex where spastic paraplegia is complicated with additional neurological features, and are inherited in autosomal dominant, autosomal recessive or X-linked patterns. Genetic defects have been identified in over 40 different genes, with more than 70 loci in total. Complex recessive spastic paraplegias have in the past been frequently associated with mutations in SPG11 (spatacsin), ZFYVE26/SPG15, SPG7 (paraplegin) and a handful of other rare genes, but many cases remain genetically undefined. The overlap with other neurodegenerative disorders has been implied in a small number of reports, but not in larger disease series. This deficiency has been largely due to the lack of suitable high throughput techniques to investigate the genetic basis of disease, but the recent availability of next generation sequencing can facilitate the identification of disease-causing mutations even in extremely heterogeneous disorders. We investigated a series of 97 index cases with complex spastic paraplegia referred to a tertiary referral neurology centre in London for diagnosis or management. The mean age of onset was 16 years (range 3 to 39). The SPG11 gene was first analysed, revealing homozygous or compound heterozygous mutations in 30/97 (30.9%) of probands, the largest SPG11 series reported to date, and by far the most common cause of complex spastic paraplegia in the UK, with severe and progressive clinical features and other neurological manifestations, linked with magnetic resonance imaging defects. Given the high frequency of SPG11 mutations, we studied the autophagic response to starvation in eight affected SPG11 cases and control fibroblast cell lines, but in our restricted study we did not observe correlations between disease status and autophagic or lysosomal markers. In the remaining cases, next generation sequencing was carried out revealing variants in a number of other known complex spastic paraplegia genes, including five in SPG7 (5/97), four in FA2H (also known as SPG35) (4/97) and two in ZFYVE26/SPG15 Variants were identified in genes usually associated with pure spastic paraplegia and also in the Parkinson's disease-associated gene ATP13A2, neuronal ceroid lipofuscinosis gene TPP1 and the hereditary motor and sensory neuropathy DNMT1 gene, highlighting the genetic heterogeneity of spastic paraplegia. No plausible genetic cause was identified in 51% of probands, likely indicating the existence of as yet unidentified genes.
Project description:To identify a novel disease gene in 2 families with autosomal recessive hereditary spastic paraplegia (HSP).We used whole-exome sequencing to identify the underlying genetic disease cause in 2 families with apparently autosomal recessive spastic paraplegia. Endogenous expression as well as subcellular localization of wild-type and mutant protein were studied to support the pathogenicity of the identified mutations.In 2 families, we identified compound heterozygous or homozygous mutations in the kinesin gene KIF1C to cause hereditary spastic paraplegia type 58 (SPG58). SPG58 can be complicated by cervical dystonia and cerebellar ataxia. The same mutations in a heterozygous state result in a mild or subclinical phenotype. KIF1C mutations in SPG58 affect the domains involved in adenosine triphosphate hydrolysis and microtubule binding, key functions for this microtubule-based motor protein.KIF1C is the third kinesin gene involved in the pathogenesis of HSPs and is characterized by a mild dominant and a more severe recessive disease phenotype. The identification of KIF1C as an HSP disease gene further supports the key role of intracellular trafficking processes in the pathogenesis of hereditary axonopathies.