KIAA0196 Research Articles

SPG8 mutations in Italian families: clinical data and literature review.

Spastic paraplegia type 8 (SPG8) is an autosomal-dominant form of hereditary spastic paraplegia (AD-HSP) caused by a mutation in the KIAA0196 gene. SPG8 accounts for 1% of less of all AD-HSP and the genotype-phenotype correlation remains poorly understood. We report the first clinical and genetic description of SPG8 disease in Italian patients. We identified four new mutations in KIAA0196 gene. These variants were identified using a multigene targeted resequencing HSP panel. We took this opportunity to review the pertinent literature. Age at disease onset was in the third or fourth decade of life. Stiffness of the lower limb with spastic gait, walking impairment, and decreased vibration sense were common early symptoms. Subjects of two families had bladder control abnormalities. Unlike previous reported cases, Italian SPG8 subjects have pure form of spastic paraparesis without cranial nerve involvement, and onset is in adult life. By a clinical point of view, it is hard to differentiate SPG8 from the SPG4, in which bladder and vibration sense dysfunctions are frequent signs. The differential diagnosis with other forms of AD-HSPs seems relatively easier if one considers the early-onset manifestations in SPG3A and the peripheral nervous system and cerebellar involvement seen in SPG31.

Establishment and preliminary mechanism study of the zebrafish strain of KIAA0196: A candidate pathogenic gene for heart development

To explore the effects of KIAA0196 gene on cardiac development and the establishment of zebrafish strain. Methods: Peripheral blood and gDNA from patients were extracted. Copy number variation analysis and target sequencing were conducted to screen candidate genes. The KIAA0196 knockout zebrafish was generated by CRISPR/Cas9 to detect whether KIAA0196 deficiency could affect cardiac development. Finally, the wild-type and mutant zebrafish were anatomized and histologically stained to observe the phenotype of heart defects. Results: The KIAA0196 knockout zebrafish strain was successfully constructed using CRISPR/Cas9 technology. After 60 hours fertilization, microscopic examination of KIAA0196 knockout zebrafish (heterozygote + homozygote) showed pericardial effusion, cardiac compression and severely curly tail. Compared with wild-type zebrafish, the hearts of mutant KIAA0196 zebrafish had cardiac defects including smaller atrium and larger ventricle, and the myocardial cells were looser. Conclusion: KIAA0196 gene plays an important regulatory role in the development of heart. It might be a candidate gene for congenital heart disease.

Targeted next‑generation sequencing for research and diagnostics in congenital heart disease, and cleft lip and/or palate.

Congenital heart disease(CHD), and cleft lip and palate(CLP) are currently the most common types of structural malformation in infants. Various methods have been used to identify the disease‑associated genes. However, targeted next‑generation sequencing(NGS) is not yet considered an option for routine use. Thus, the present study aimed to assess the safety and feasibility of using targeted NGS in patients with CHD concomitant with CLP. Between November2015 and May2017, a total of 17patients with CHD concomitant with CLP, who were excluded from a diagnosis of trisomy syndrome, were selected at The Second Xiangya Hospital of Central South University (Changsha, China). Genomic DNA was extracted from peripheral blood samples of the patients. The copy number variants(CNVs) were determined by conducting a single nucleotide polymorphism (SNP) array with Illumina HumanOmni1‑Quad Beadchip, while information on other gene mutations was obtained from targeted sequencing. The functions of gene mutations were then predicted using the PolyPhen‑2, SIFT and Mutation Taster tools. Finally, Sanger sequencing was used to verify the mutations. The results identified no pathogenic mutations in CNVs analyzed by high‑throughput SNP sequencing. Targeted NGS results demonstrated that 10patients(58.8%) carried gene mutations, including 4(23.5%) genetically diagnosed cases and 6(35.3%) cases with unknown etiology. The 4 known diseases were Opitz G/BBB syndrome caused by MID1 gene mutation, Loeys‑Dietz syndrome caused by TGFBR1 gene mutation, Ritscher‑Schinzel/3C syndrome caused by KIAA0196 gene mutation and CHARGE syndrome caused by CHD7 gene mutation. The remaining 6 cases were not genetically diagnosed, although they carried candidate genes. In conclusion, the present study demonstrated that targeted NGS was an effective and accurate candidate gene detection method in patients with CHD concomitant with CLP.

Exome sequencing expands the mutational spectrum of SPG8 in a family with spasticity responsive to l-DOPA treatment

Dear Sirs, Hereditary spastic paraplegias (HSPs) are clinically and genetically heterogeneous. Pure forms are characterized primarily by progressive spasticity and weakness of the lower limbs. Complicated forms, however, involve neuronal systems other than corticospinal tracts, namely peripheral nerves, and sensory or cerebellar pathways [2]. At least 52 loci and 31 causative genes are known, and thus a gene-by-gene diagnostic approach is becoming impractical. For the 19 autosomal dominant forms (AD-HSPs), 11 genes are known, with SPG4 being by far the most common subtype (40–45 % AD-HSP cases) [4]. The vast heterogeneity in HSP makes a genetic diagnosis difficult and expensive. Many research groups have used gene panels or targeted sequencing but the rapid growth and frequent identification of new genes makes this difficult. We studied a female patient presenting familial spastic paraplegia with sensory axonal neuropathy, compatible with AD inheritance (Fig. 1a). At the age of 10 years she developed problems walking and subsequently had many surgical procedures on her feet. After a pregnancy at the age of 42, she became more tired and walking slowed down with more pain. She has significant spasticity and sensory symptoms in her feet, burning, redness, occasionally whiteness, and she is often in extreme pain and discomfort. Both brain and spinal cord MRI scans were normal. She was started on l-DOPA (Co-Careldopa 25/100 mg tds), as one of the differential diagnoses was dopamine responsive dystonia, which was very helpful for her spasms and sensory symptoms in her feet. Additionally, she had bladder urgency and skin features to suggest autonomic dysfunction, and her gait was typical of spastic paraplegia. Her daughter reported early problems presenting at the age of 19, with pain in her feet and in the back of her legs, spasticity, cramps and sensory symptoms. Her gait showed a slight inversion of the right foot on walking. Interestingly, the daughter had tried l-DOPA in the form of Co-Careldopa 25/100 mg with benefit to her spasticity similar to her mother. The proband’s mother was also thought to have feet problems, with cold and stiff painful feet as well as abnormal sensation but her presentation was late in her mid-50s with very slow deterioration. Fig. 1 a Pedigree of a UK family with spastic paraplegia. The arrow points to the proband. Black and white symbols indicate affected and unaffected individuals, respectively. b Electropherograms illustrating the novel KIAA0196 missense variant (c.677T > C, ... Although whole-exome sequencing is still expensive, and not everywhere available, it has been shown to be a useful tool for the diagnosis of complicated HSP [1]. Using this approach, we identified a novel KIAA0196 missense variant in the proband (c.677T>C, p.I226T). By Sanger sequencing, her daughter was shown to have the same variant (Fig. 1b). This variant is predicted as damaging by SIFT, is located in a conserved residue (Fig. 1c), and is not present in more than 200 in-house exomes or in public databases, such as dbSNP, 1000 Genomes Project, and the Exome Variant server (http://evs.gs.washington.edu/EVS/). The KIAA0196 gene (MIM#610657) is responsible for SPG8 (MIM#603563), a rare AD-HSP, and encodes for strumpellin, a protein that participates in the WASH complex, acting at the interface between actin regulation and endosomal membrane dynamics [5]. There are only two reports of mutations in this gene [3, 8], one of them recently published in this journal. Overall, there are seven SPG8 families, usually with pure phenotypes, and four pathogenic mutations identified worldwide (Table 1). Our pedigree is compatible with an AD-HSP, and the variant we found in the KIAA0196 gene, segregating with the phenotype, is most likely causing HSP. The response to l-DOPA is interesting and may suggest an overlap of the functional pathway of KIAA0196 and dopamine. Although the knowledge of the underlying mutation does not change the therapeutic strategy, it is valuable on what concerns genetic counseling. We therefore identified the eighth SPG8 family and the fifth mutation by making use of next-generation sequencing. Furthermore, we report a complicated phenotype, with an earlier onset than those previously reported (Table 1), also expanding the clinical spectrum of SPG8. Table 1 Mutations in the KIAA0196 gene identified in HSP families

Pure adult-onset Spastic Paraplegia caused by a novel mutation in the KIAA0196 (SPG8) gene

SPG8 is a rare autosomal dominant hereditary spastic paraplegia (AD-HSP), with only six SPG8 families described so far. Our purpose was to screen for KIAA0196 (SPG8) mutations in AD-HSP patients and to investigate their phenotype. Extensive family investigation was performed after positive KIAA0196 mutation analysis, which was part of an on-going mutation screening effort in AD-HSP patients. A novel pathogenic KIAA0196 mutation p.(Gly696Ala) was identified in two AD-HSP patients, who subsequently were shown to belong to a single large Dutch pedigree with more than 10 affected family members. The phenotype consisted of a pure HSP with ages at onset between 20 and 60 years, distally reduced vibration sense in the legs in all, and urinary urgency in seven out of 10 patients. Frequent features were exercise- or emotion-induced increase of spasticity and gait problems and chronic nonspecific lower back and joint pains. We have identified a fourth pathogenic KIAA0196 mutation in a Dutch HSP-family, the seventh family worldwide, with a less severe clinical course than described before.

Hereditary spastic paraplegia caused by a mutation in the VCP gene

Sir, The hereditary spastic paraplegias constitute a genetically and clinically heterogeneous group of disorders of which the main clinical feature is progressive lower limb spasticity due to pyramidal tract dysfunction. The cardinal signs result from a ‘dying back’ degeneration of the corticospinal tracts and dorsal column, predominantly due to disturbed axonal transport within the longest fibres that innervate the lower extremities. Currently, among the 52 known hereditary spastic paraplegia genetic loci named SPG1–52, at least 28 genes have been identified. One of the rarer autosomal dominant forms of hereditary spastic paraplegia, SPG8, is caused by mutations in the KIAA0196 gene on chromosome 8, encoding the protein strumpellin. In an interesting report in Brain by Clemen et al. (2010), strumpellin was demonstrated to interact with the valosin-containing protein (VCP), suggesting a complementary biological function. Also, strumpellin was detected in several pathological protein aggregates, including those seen in autosomal-dominant inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD; OMIM 605382) (Clemen et al. , 2010). Mutations in the human VCP gene itself cause either IBMPFD or amyotrophic lateral sclerosis with or without frontotemporal dementia (Watts et al. , 2004; Haubenberger et al. , 2005; Guyant-Marechal et al. , 2006; Gidaro et al. , 2008; Bersano et al. , 2009; Johnson et al. , 2010; Fanganiello et al. , 2011; Jesus-Hernandez et al. , 2011; Nalbandian et al. , 2011). Although the paper by Clemen et al. (2010), based on this interaction between VCP and strumpellin, could suggest that VCP mutations may perhaps lead to an hereditary spastic paraplegia phenotype, this has not yet been reported. We recently saw two brothers, both affected by a slowly progressive spastic paraplegia and Paget’s disease of bone, in whom we identified a …

Strumpellin is a novel VCP/p97-binding protein linking hereditary spastic paraplegia to protein aggregation diseases

Strumpellin is a novel VCP/p97-binding protein linking hereditary spastic paraplegia to protein aggregation diseases

Mutations in the KIAA0196 Gene at the SPG8 Locus Cause Hereditary Spastic Paraplegia

Hereditary spastic paraplegia (HSP) is a progressive upper-motor neurodegenerative disease. The eighth HSP locus, SPG8, is on chromosome 8p24.13. The three families previously linked to the SPG8 locus present with relatively severe, pure spastic paraplegia. We have identified three mutations in the KIAA0196 gene in six families that map to the SPG8 locus. One mutation, V626F, segregated in three large North American families with European ancestry and in one British family. An L619F mutation was found in a Brazilian family. The third mutation, N471D, was identified in a smaller family of European origin and lies in a spectrin domain. None of these mutations were identified in 500 control individuals. Both the L619 and V626 residues are strictly conserved across species and likely have a notable effect on the structure of the protein product strumpellin. Rescue studies with human mRNA injected in zebrafish treated with morpholino oligonucleotides to knock down the endogenous protein showed that mutations at these two residues impaired the normal function of the KIAA0196 gene. However, the function of the 1,159-aa strumpellin protein is relatively unknown. The identification and characterization of the KIAA0196 gene will enable further insight into the pathogenesis of HSP.