Agata Gajos

High variability of clinical symptoms in a Polish family with a novel THAP1 mutation

Background. Mutations in the THAP1 gene are associated with a broad spectrum of dystonia including focal and generalized forms. Missense, nonsense and frameshift mutations, including small insertions/deletions within the THAP1 gene, have been reported and majority of them cause autosomal dominant disease with limited penetrance of approximately 60%. Here, we describe a novel THAP1 mutation. Materials and methods. Blood samples were collected from consenting family members for extraction of genomic DNA. As controls, we analyzed 150 individuals without neurological disorders. THAP1 coding sequences were amplified with PCR and sequenced. Results. We describe a Polish family with a novel heterozygous substitution: c.167A>G (p.Glu56Gly) in THAP1 exon 2. This is the largest reported family with the mutation in THAP1 exon 2. The mutation was found in four of five genetically studied family members, including two clinically affected male individuals and two asymptomatic carriers (male and female). Data on one deceased male symptomatic subject were available and two assumed carriers were identified. The substitution was not present in any of the analyzed healthy controls. The high variability of phenotype included age of onset, localization of the initial symptom as well as the rate and degree of generalization. Conclusions. Our findings strongly suggest the role of other genetic factors or environmental triggers in the pathogenesis of dystonia related to mutations in THAP1 gene.

Spectral optical coherence tomography in a patient with type I sialidosis.

Summary Background The aim of our study was to analyze spectral optical coherence tomography (SD-OCT) findings in a patient with clinical signs of sialidosis. Case Report Fluorescein angiography and spectral optical coherence tomography was performed in a 37-year-old woman using a SD-OCT device with axial resolution of 6 μm. Enzyme assay followed. The patient was diagnosed with type I sialidosis by enzymatic assay. Besides a normal angiogram, a thickened nerve fiber layer was observed on spectral optical coherence tomography. Conclusions The thickened nerve fiber layer was probably caused by accumulation of metabolic products such as sialylated oligosaccharides and glycopeptides, suggesting that SD- OCT, due to its enhanced resolution, can be a useful tool for diagnosis of rare neurological conditions.

Dystrophic neurites accumulating autophagic vacuoles show early stages of neuritic destruction

We re-examined the database of some 20,000 electron micrographs from the Echigo-1, the 263K-strain or the 22C-H of scrapie-infected hamsters to look for the cytoplasmic clearance. We reevaluated the largest database in the world of photographed dystrophic neurites for the presence of cytoplasmic clearance as shown in transgenic fruit flies transfected with A-42. In several neurites, we found electron-lucent areas not bound by any membranes or only partially bound; thus, they were not autophagic vacuoles as the latter are membrane-bound and contain cargo. Those changes were not observed in every examined neurite and no correlation with any other changes were noticed. In some neurites, which could be traced over several sections, the electron-lucent areas were evident to change size, i.e. to expand.

Electron microscopic and confocal laser microscopy analysis of amyloid plaques in chronic wasting disease transmitted to transgenic mice

Abstract We report here on the ultrastructure of amyloid plaques in chronic wasting disease (CWD) transmitted to Tg20 transgenic mice overexpressing prion protein (PrPc). We identified three main types of amyloid deposits in mCWD: large amyloid deposits, unicentric plaques similar to kuru plaques in human prion diseases and multicentric plaques reminiscent of plaques typical of GSS. The most unique type of plaques were large subpial amyloid deposits. They were composed of large areas of amyloid fibrils but did not form „star-like” appearances of unicentric plaques. All types of plaques were totally devoid of dystrophic neuritic elements. However, numerous microglial cells invaded them. The plaques observed by confocal laser microscope were of the same types as those analyzed by electron microscopy. Neuronal processes surrounding the plaques did not show typical features of neuroaxonal dystrophy.

Robust autophagy in optic nerves of experimental Creutzfeldt-Jakob disease and Gerstmann-Sträussler-Scheinker disease

We report here autophagy in the optic nerve in experimental Gerstmann-Sträussler-Scheinker disease (GSS) (Fujisaki-1) in mice and experimental Creutzfeldt-Jakob disease (CJD) (Echigo-1) in hamsters. Lesions of both experimental GSS in mice and experimental CJD in hamsters were practically indistinguishable. Briefly, they consisted of widespread Wallerian degeneration, spongiform change and a glial reaction. Numerous axonal swellings were seen. The latter were filled with numerous mitochondria and lysosomal electron-dense bodies. Autophagic vacuoles defined as structures bound in double membranes were readily found in many neuronal processes. The following description is organized as a sequence; however, the changes were all observed in the same specimens. First several empty double membrane-bound autophagic vacuoles were seen. In several of those vacuoles, the inner membrane was separated from the outer membrane and enclosed cargo. At the final stage, a mixture of empty autophagic vacuoles and electron-dense lysosomal vesicles was seen. Dystrophic neurites filled with a mixture of mitochondria, empty autophagic vacuoles and electron-dense lysosomal vesicles were interpreted as the final stage of autophagy. Of note, several areas were replaced with dense astrocytic gliosis..

Unilateral progressive muscular atrophy with fast symptoms progression

Progressive muscular atrophy (PMA), or the lower motor neuron disease, is a sporadic disorder characterized by onset in adulthood, pure lower motor neuron involvement and relatively benign course. Muscle atrophy and weakness may be symmetrical or asymmetrical, but they are always bilateral. We present a male patient with exclusively left-side flaccid paresis due to lower motor neuron disease without electromyographic evidence of neurogenic lesion of contralateral muscles and with no signs of corticospinal tracts involvement. The rapid disease progression was typical of the generalized phenotype of PMA and it suggested the relation to the aggressive course of classical ALS.

Screening for THAP1 Mutations in Polish Patients with Dystonia Shows Known and Novel Substitutions

The aim of this study was to assess the presence of DYT6 mutations in Polish patients with isolated dystonia and to characterize their phenotype. We sequenced THAP1 exons 1, 2 and 3 including exon-intron boundaries and 5’UTR fragment in 96 non-DYT1 dystonia patients. In four individuals single nucleotide variations were identified. The coding substitutions were: c. 238A>G (p.Ile80Val), found in two patients, and c.167A>G (p.Glu56Gly), found in one patient. The same variations were present also in the patients’ symptomatic as well as asymptomatic relatives. Mutation penetration in the analyzed families was 50-66.7%. In the fourth patient, a novel c.-249C>A substitution in the promoter region was identified. The patient, initially suspected of idiopathic isolated dystonia, finally presented with pantothenate kinase 2-associated neurodegeneration phenotype and was a carrier of two PANK2 mutations. This is the first identified NBIA1 case carrying mutations in both PANK2 and THAP1 genes. In all symptomatic THAP1 mutation carriers (four probands and their three affected relatives) the first signs of dystonia occurred before the age of 23. A primary localization typical for DYT6 dystonia was observed in six individuals. Five subjects developed the first signs of dystonia in the upper limb. In one patient the disease began from laryngeal involvement. An uncommon primary involvement of lower limb was noted in the THAP1 and PANK2 mutations carrier. Neither of these THAP1 substitutions were found in 150 unrelated healthy controls. To the contrary, we identified a heterozygous C/T genotype of c.57C>T single nucleotide variation (p.Pro19Pro, rs146087734) in one healthy control, but in none of the patients. Therefore, a previously proposed association between this substitution and DYT6 dystonia seems unlikely. We found also no significant difference between cases and controls in genotypes distribution of the two-nucleotide -237-236 GA>TT (rs370983900 & rs1844977763) polymorphism.