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FARAFARA Cure FA

 

Scientific News

FARA funds research progress

In this section, you will find the most recent FA research publications, many of which are funded by FARA, as well as information on upcoming conferences and symposiums. You can search for articles by date using the archive box in the right hand column. To locate FARA Funded or Supported Research, click the hyperlink in the right hand column. You may also search for specific content using key words or phrases in the search button at the top right of your screen. Please be sure to visit other key research sections of our website for information on FARA’s Grant Program and the Treatment Pipeline.

 


 

Pitfalls in molecular diagnosis of Friedreich ataxia

Freidreich ataxia (FRDA) is the most common hereditary ataxia, nearly 98% of patients harbouring homozygous GAA expansions in intron 1 of the FXN gene (NM_000144.4). The remaining patients are compound heterozygous for an expansion and a point mutation or an exonic deletion. Molecular screening for FXN expansion is therefore focused on (GAA)n expansion analysis, commonly performed by triplet repeat primed PCR (PT-PCR). We report on an initial pitfall in the molecular characterization of a 15 year-old girl with Freidreich ataxia (FRDA) who carried a rare deletion in intron 1 of the FXN gene. Due to this deletion TP-PCR failed to amplify the GAA expansion. This exceptional configuration induced misinterpretation of the molecular defect in this patient, who was first reported as having no FXN expansion. NGS analysis of a panel of 212 genes involved in nuclear mitochondrial disorders further revealed an intragenic deletion encompassing exons 4-5 of the FXN gene. Modified TP-PCR analysis confirmed the presence of a classical (GAA)n expansion located in trans. This case points out the possible pitfalls in molecular diagnosis of FRDA in affected patients and their relatives: detection of the FXN expansion may be impaired by several non-pathological or pathological variants around the FXN (GAA)n repeat. We propose a new molecular strategy to accurately detect expansion by TP-PCR in FRDA patients.

Read the entire article HERE

Bone marrow transplantation stimulates neural repair in Friedreich's ataxia mice

OBJECTIVES:Friedreich's ataxia is an incurable inherited neurological disease caused by frataxin deficiency. Here we report the neuro-reparative effects of myeloablative allogeneic bone marrow transplantation in a humanised murine model of the disease.
METHODS:Mice received a transplant of fluorescently-tagged sex mis-matched bone marrow cells expressing wild-type frataxin and were assessed at monthly intervals using a range of behavioural motor performance tests. At six months post-transplant, mice were sacrificed for protein and histological analysis. In an attempt to augment numbers of bone marrow-derived cells integrating within the nervous system and improve therapeutic efficacy, a sub-group of transplanted mice also received monthly subcutaneous infusions of cytokines granulocyte-colony stimulating factor and stem cell factor.
RESULTS:Transplantation caused improvements in several indicators of motor coordination and locomotor activity. Elevations in frataxin levels and anti-oxidant defences were detected. Abrogation of disease pathology throughout the nervous system was apparent, together with extensive integration of bone marrow-derived cells in areas of nervous tissue injury that contributed genetic material to mature neurons, satellite-like cells and myelinating Schwann cells by processes including cell fusion. Elevations in circulating bone marrow-derived cell numbers were detected post-cytokine administration and were associated with increased frequencies of Purkinje cell fusion and bone marrow-derived dorsal root ganglion satellite-like cells. Further improvements in motor coordination and activity were evident.
INTERPRETATION:Our data provide proof-of-concept of gene replacement therapy, via allogeneic bone marrow transplantation, that reverses neurological features of Friedreich's ataxia with the potential for rapid clinical translation.

Read the entire article HERE

Biophysical characterisation of the recombinant human frataxin precursor

Friedreich's ataxia is a disease caused by a decrease in the levels of expression or loss of functionality of the mitochondrial protein frataxin (FXN). The development of an active and stable recombinant variant of FXN is important for protein replacement therapy. Although valuable data about the mature form FXN81-210 has been collected, not enough information is available about the conformation of the frataxin precursor (FXN1-210). This group investigated the conformation, stability and function of a recombinant precursor variant (His6-TAT-FXN1-210), which includes a TAT peptide in the N-terminal region to assist with transport across cell membranes. His6-TAT-FXN1-210 was expressed in Escherichia coli and conditions were found for purifying folded protein free of aggregation, oxidation or degradation, even after freezing and thawing. The protein was found to be stable and monomeric, with the N-terminal stretch (residues 1-89) mostly unstructured and the C-terminal domain properly folded. The experimental data suggest a complex picture for the folding process of full-length frataxin in vitro: the presence of the N-terminal region increased the tendency of FXN to aggregate at high temperatures but this could be avoided by the addition of low concentrations of GdmCl. The purified precursor was translocated through cell membranes. In addition, immune response against His6-TAT-FXN1-210 was measured, suggesting that the C-terminal fragment was not immunogenic at the assayed protein concentrations. Finally, the recognition of recombinant FXN by cellular proteins was studied to evaluate its functionality. In this regard, cysteine desulfurase NFS1/ISD11/ISCU was activated in vitro by His6-TAT-FXN1-210. Moreover, the results showed that His6-TAT-FXN1-210 can be ubiquitinated in vitro by the recently identified frataxin E3 ligase RNF126, in a similar way as the FXN1-210, suggesting that the His6-TAT extension does not interfere with the ubiquitination machinery.

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Small RNA-seq analysis of circulating miRNAs to identify phenotypic variability in Friedreich's ataxia patients

Friedreich's ataxia, an autosomal recessive neurodegenerative mitochondrial disease, is the most prevalent hereditary ataxia. In addition, FRDA patients have shown additional non-neurological features such as scoliosis, diabetes, and cardiac complications. Hypertrophic cardiomyopathy, which is found in two thirds of patients at the time of diagnosis, is the primary cause of death in these patients. This group used small RNA-seq of microRNAs (miRNAs) purified from plasma samples of FRDA patients and controls. They present the rationale, experimental methodology, and analytical procedures for dataset analysis. This dataset will facilitate the identification of miRNA signatures and provide new molecular explanation for pathological mechanisms occurring during the natural history of FRDA. Since miRNA levels change with disease progression and pharmacological interventions, miRNAs will contribute to the design of new therapeutic strategies and will improve clinical decisions.

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Progress in the treatment of Friedreich ataxia

Friedreich ataxia (FRDA) is a progressive neurological disorder affecting approximately 1 in 29,000 individuals of European descent. At present, there is no approved pharmacological treatment for this condition however research into treatment of FRDA has advanced considerably over the last two decades since the genetic cause was identified. Current proposed treatment strategies include decreasing oxidative stress, increasing cellular frataxin, improving mitochondrial function as well as modulating frataxin controlled metabolic pathways. Genetic and cell based therapies also hold great promise. Finally, physical therapies are being explored as a means of maximising function in those affected by FRDA.

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