VPS53 gene is associated with a new phenotype of complicated hereditary spastic paraparesis.

Hereditary spastic paraparesis (HSP) is a progressive neurodegenerative disorder, characterized by progressive lower limb weakness and spasticity. Multiple genes are associated with both the pure and complicated HSP types. Our study is aimed at seeking for novel genetic basis of HSP in a family with two affected siblings. Genetic analysis using whole exome sequencing was conducted in a family quartet with two female siblings, who presented with complicated HSP featuring slowly progressive paraparesis, mild-moderate intellectual disability, normal head circumference (HC), and normal magnetic resonance imaging (MRI). A homozygous pathogenic variant was identified in both siblings in the VPS53 gene (c.2084A>G: c.2084A>G, p.Gln695Arg). This gene acts as a component of the Golgi-associated retrograde protein (GARP) complex that is involved, among others, in intracellular cholesterol transport and sphingolipid homeostasis in lysosomes and was previously associated with progressive cerebello-cerebral atrophy (PCCA) type 2. This is the first description of the VPS53 gene as a cause of autosomal recessive complicated HSP. Lysosomal dysfunction as a result of impaired cholesterol trafficking can explain the neurodegenerative processes responsible for the HSP. Our finding expands the phenotype of VPS53-related disease and warrants the addition of VPS53 analysis to the genetic investigation in patients with autosomal recessive HSP. The exact role of GARP complex in neurodegenerative processes should be further elucidated.

Complete clinical and functional recovery following low-dose methotrexate related paraparesis in a patient with compound c.1298A>C AND c.677C>T MTHFR polymorphism: A case report.

RATIONALE: The mechanisms of action of MTX (methotrexate) in the treatment of RA (rheumatoid arthritis) and PsA (psoriatic arthritis) is related to its antifolic activity, due to the high affinity for enzymes that require folate cofactors as dihydrofolate reductase and to the anti-inflammatory activity derivated from the inhibition of thymidylate synthetase that leads to the over-production of adenosine. PATIENT CONCERNS: Our patient was a 41-year-old female, affected by PsA in treatment since 2 years with low-dose methylprednisolone and low-dose subcutaneous MTX. The treatment was effective. The patient subacutely developed a severe paraparesis with impossibility of gait or standing without aid and was admitted to a Neurology Department where the cause of the paraparesis was not clear in spite of accurate radiological neurophysiologic and laboratory tests. Therefore, she was admitted in a rehabilitation unit. DIAGNOSIS AND INTERVENTIONS: Paraparesis in PsA patient in treatment with methotrexate. MTX toxicity was hypothesized; therefore the drug was discontinued while i.m. folic acid and cyanocobalamin were administered for 20 days. The diagnosis was clinical, based on neurological examination (paraparesis) and on the chronic use of MTX (hypothesis of toxicity). OUTCOMES: The patient obtained a complete resolution of paraparesis. Genetic analyses showed associated a compound heterozygosity for the c.1298A>C and c.677C>T variants of methylenetetrahydrofolate reductase (MTHFR) gene. LESSONS: Neurological side effects of MTX are uncommon. In literature no previous case of MTX induced paraparesis in patients treated with low-dose MTX for chronic arthritis has been described. The association between the gene polymorphisms of MTHFR (c.1298A>C and c.677C>T) and MTX toxicity in arthritis patients is confirmed. The case also confirms that folates are a precious antidote of MTX toxicity.

Hereditary ataxias and paraparesias: clinical and genetic update.

PURPOSE OF REVIEW: This review aims at updating the clinical and genetic aspects of hereditary spastic paraplegias (HSPs) and hereditary cerebellar ataxias (HCAs), focusing on the concept of spastic-ataxia phenotypic spectrum and on newly identified clinical overlaps with other neurological and nonneurological diseases. RECENT FINDINGS: Next-generation sequencing (NGS) has allowed the discovery of new genes involved in HSPs and HCAs. They include new HCAs genes such as GRM1 (SCA44), FAT2 (SCA45), PLD3 (SCA46), SCYL1 (SCAR21), UBA5 (SCAR24) and XRCC1 (SCAR26) as well as CAPN1 (SPG76) and CPT1C (SPG73) in HSPs. Furthermore, NGS allowed enriching known genes phenotype, reinforcing the overlap between HSPs and HCAs defining the spastic ataxia spectrum. Clear examples are the expanded phenotypes associated with mutations in SPG7, PNPLA6, GBA2, KIF1C, CYP7B1, FA2H, ATP13A2 and many others. Moreover, other genes not previously linked to HCAs and HSPs have been implicated in spastic or ataxic phenotypes. SUMMARY: The increase of HSPs and HCAs-related phenotypes and the continuous discovery of genes complicate clinical diagnostic in practice but, at the same time, it helps highlighting common pathological pathways, therefore opening new ways to the development of common therapeutic approaches.

Histopathological proof of the pathogenicity of a rare GFAP mutation in a patient with flaccid paraparesis.

Infantile Alexander disease is a rare progressive leukodystrophy caused by autosomal dominant mutations in the (GFAP) gene typically presenting with psychomotor retardation, progressive macrocephaly and refractory epilepsy. Neuroradiological hallmarks are extensive white matter lesions with frontal preponderance as well as signal intensity changes of basal ganglia and medulla oblongata with variable contrast enhancement. Here, we report an atypical manifestation in a 21-month-old boy presenting with flaccid paraparesis and areflexia. Cognitive, visual as well as fine motor skills and muscular strength of the upper extremities were appropriate for age. Weight and height as well as head circumference were within normal range. Clinical or electroencephalographic signs of seizures were absent. Cranial MRI demonstrated bifrontal cystic tumorous lesions with partial contrast rims, as well as space-occupying focal lesions of the caudate nuclei. Spinal MRI revealed swelling of the lumbar and cervical spinal cord. CSF and blood chemistry showed normal results. Histopathology of a subcortical lesion showed large amounts of Rosenthal fibers and protein droplets characteristic of Alexander disease. Sequencing detected a heterozygous mutation of the GFAP gene (c.205G > A; p.(Glu69Lys)) that has been reported before as probably pathogenetic in another case of lower spinal involvement. This well documented case draws attention to atypical spinal manifestations of Alexander disease and gives histopathological proof of the pathogenetic role of a rare GFAP mutation with marked spinal involvement.

Proximal paraparesis due to aortic dissection extending into bilateral carotid arteries in a patient with Loeys-Dietz syndrome.

The authors report a 66 year-old female with past medical history relevant for thoracic abdominal aneurysm who presented with a complaint of chest pain radiating into her neck. The physical examination was significant for the distinctive facial features of wide spaced eyes and V-shaped uvula. Thoracic CT scan revealed a type I aortic dissection which warranted immediate surgical repair. On post-op day one she was noted to be confused and was found to have acute bilateral lower extremity paraparesis with proximal predominance. Furthermore, her left radial artery line had no pulse waves and no brachial, radial, or ulnar pulses could be detected with Doppler ultrasound. Emergent head CT scan revealed bilateral postcentral gyri infarctions and the thoracic CT scan demonstrated extension of the dissection into the aortic branches, including the left brachial and the bilateral carotid arteries. Consequently, surgical brachial artery repair ensued. In the interim, a repeated head CT scan demonstrated new ischemic infarcts involving the bilateral frontal lobes. Anticoagulation was not indicated due to the high risk of bleeding at surgical site. Genetic testing confirmed the presence of a mutation in the TGFBR2 gene at exon 5. Loeys-Dietz syndrome is an autosomal dominant disease caused by heterozygous mutations in the genes encoding type I or II transforming growth factor-ß (TGF-ß) receptor. Loeys-Dietz syndrome manifests with aggressive vascular pathology. This case underscores the importance of recognition of this spectrum of clinical and pathologic manifestations to identify and manage Loeys-Dietz syndrome.

Corticospinal tract MRI hyperintensity in X-linked Charcot-Marie-Tooth Disease.

In X-linked hereditary demyelinating neuropathies (CMTX), caused by mutations in Connexin 32, mild subclinical CNS involvement is not unusual. We present a young male patient suffering from genetically proven CMTX who presented with permanent bilateral corticospinal tract hyperintensities in cranial MRI -- a finding previously described to be characteristic for amyotrophic lateral sclerosis. MRI seems to be able to visualize corticospinal tract abnormalities, even if subclinical, in CMTX.

Heterozygous missense mutations in BSCL2 are associated with distal hereditary motor neuropathy and Silver syndrome.

Distal hereditary motor neuropathy (dHMN) or distal spinal muscular atrophy (OMIM #182960) is a heterogeneous group of disorders characterized by an almost exclusive degeneration of motor nerve fibers, predominantly in the distal part of the limbs. Silver syndrome (OMIM #270685) is a rare form of hereditary spastic paraparesis mapped to chromosome 11q12-q14 (SPG17) in which spasticity of the legs is accompanied by amyotrophy of the hands and occasionally also the lower limbs. Silver syndrome and most forms of dHMN are autosomal dominantly inherited with incomplete penetrance and a broad variability in clinical expression. A genome-wide scan in an Austrian family with dHMN-V (ref. 4) showed linkage to the locus SPG17, which was confirmed in 16 additional families with a phenotype characteristic of dHMN or Silver syndrome. After refining the critical region to 1 Mb, we sequenced the gene Berardinelli-Seip congenital lipodystrophy (BSCL2) and identified two heterozygous missense mutations resulting in the amino acid substitutions N88S and S90L. Null mutations in BSCL2, which encodes the protein seipin, were previously shown to be associated with autosomal recessive Berardinelli-Seip congenital lipodystrophy (OMIM #269700). We show that seipin is an integral membrane protein of the endoplasmic reticulum (ER). The amino acid substitutions N88S and S90L affect glycosylation of seipin and result in aggregate formation leading to neurodegeneration.

Age-dependent paraparesis in WKA rats: evaluation of MHC k-haplotype and HTLV-1 infection.

Human T-cell leukemia virus type 1 (HTLV-1) infection is shown to be closely associated with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the occurrence of HAM/TSP was reported to be associated with MHC class II, the mechanism is still unclear. The WKA(RT1k) strain of rats was reported to develop HAM/TSP-like paraparesis after HTLV-1 infection, and was suggested to be an animal model of HAM/TSP. We asked whether MHC k-haplotype is specifically involved in the pathogenesis of paraparesis of WKA(RT1k) rats. We injected the HTLV-1 producing human T cells (MT-2 cells) intravenously into WKA(RT1k) rats and MHC congenic WKA.1L(RT1l) rats which have MHC l-haplotype of LEW rats on the WKA background. Positive antibody response to HTLV-1 antigens and presence of provirus in peripheral blood mononuclear cells confirmed that MT-2 cell-injected rats were infected with HTLV-1. Two of 13 MT-2 cell-injected WKA(RT1k) rats and five of 13 MT-2 cell-injected WKA.1L(RT1l) rats developed HAM/TSP-like hindlimb paraparesis between 16 and 26 months old. Interestingly, three of 14 MT-2 cell-uninjected WKA(RT1k) rats and four of 13 MT-2 cell-uninjected WKA.1L(RT1l) rats showed similar paraparesis between 15 and 26 months old. MHC k-haplotype is not specific to the development of paraparesis in WKA(RT1k) rats. The role of aging, genetic background, HTLV-1 infection and other factors on the development of HAM/TSP-like paraparesis in rats are discussed.