Metformin-dependent Exacerbation of Pathologies in Friedreich’s Ataxia

Free Radical Biology and Medicine, Volume 145, Supplement 1, 2019, Page S81, doi:10.1016/j.freeradbiomed.2019.10.216.

One case report describes metformin treatment for diabetes in a FRDA patient, he developed severe ventricular arrhythmia and died of cardiac failure during a surgery. Future research of FRDA-relevant tissues will better inform on disease exacerbation.

Left ventricular structural and functional changes in Friedreich ataxia – Relationship with body size, sex, age and genetic severity

Peverill RE, Romanelli G, Donelan L, Hassam R, Corben LA, Delatycki MB (2019); PLoS ONE 14(11): e0225147. doi:10.1371/journal.pone.0225147

In FRDA, increases in RWT and age-normalized RWT are the most frequent LV structural abnormalities, sex and body size are important determinants of most other LV structural variables in both children and adults, and increased genetic severity is associated with a smaller left ventricle and increased LV wall thickness in adults, but not associated with LV size or wall thickness in children.

Minoryx Therapeutics receives Orphan Drug Designation from the European Commission for leriglitazone in the treatment of Friedreich’s Ataxia

Mataró, Barcelona, Spain and Charleroi, Belgium, November 12, 2019 – Minoryx Therapeutics, a company that specializes in the development of innovative treatments for orphan Central Nervous System (CNS) diseases, today announces that its lead drug candidate, leriglitazone (MIN-102), has been granted Orphan Drug Designation by the European Commission in the treatment of Friedreich’s Ataxia.

Leriglitazone (MIN-102) is a novel, brain penetrant, orally bioavailable and selective PPARγ agonist that engages the target receptor within the central nervous system. The disease-modifying potential and unique mode-of-action of leriglitazone have been demonstrated in multiple preclinical CNS disease models showing that it has an anti-oxidant, anti-inflammatory and neuroprotective effect. Leriglitazone improves mitochondrial function and biogenesis, promotes remyelination, ameliorates lipid metabolism and delays the progression of neurological disability. Leriglitazone is currently in late-stage clinical development in adrenomyeloneuropathy (AMN) and Friedreich’s Ataxia (FRDA).

“We are very pleased that, following the recent FDA Orphan Drug Designation for leriglitazone in Friedreich’s Ataxia, the European Commission has also granted Orphan Drug Status, further demonstrating the potential of this novel drug candidate and our commitment to changing the lives of patients suffering from severe orphan diseases,” said Marc Martinell, CEO of Minoryx. “Leriglitazone is our lead drug candidate currently in late-stage clinical development in a number of life-threatening orphan CNS diseases. Patient enrollment has been completed in both the AMN and the FRDA studies and we are on track to present our results by the end of 2020.”

Reducing complexity: explaining inborn errors of metabolism and their treatment to children and adolescents

Nina A. Zeltner, Mendy M. Welsink-Karssies, Markus A. Landolt, Dominique Bosshard-Bullinger, Fabia Keller, Annet M. Bosch, Marike Groenendijk, Sarah C. Grünert, Daniela Karall, Beatrix Rettenbacher, Sabine Scholl-Bürgi, Matthias R. Baumgartner & Martina Huemer, Orphanet J Rare Dis 14, 248 (2019) doi:10.1186/s13023-019-1236-9

Medical jargon and incomprehensive disease information constitute a barrier to informed and shared decision-making. Over 80% of the study participants indicated that they liked the materials and appreciated them as an indicator of a respectful approach of care. Facilitated communication between patient and metabolic care team may not only enhance patients’ safety, outcome, attitude towards the care team and quality of life but does significantly reduce the workload of metabolic professionals due to increased independence of patients and families. Involvement of parents in teaching sessions and provision of the materials enables parents to explain the contents repeatedly to their child at home and to involve siblings, other family members or external caregivers to gain social support.

Temporal but not spatial dysmetria relates to disease severity in FA

Manuela Corti, Agostina Casamento Moran, Stefan Delmas, Samantha Bracksieck, Jessica Bowman, Blake Meyer, Samantha Norman, Sub Subramony, and Evangelos A Christou, Journal of Neurophysiology 0 0:0 Doi:10.1152/jn.00165.2019

The aim of this study is to characterize dysmetria and its association to functional capacity. Also, we examine the neural mechanisms of dysmetria by quantifying the EMG burst area, duration, and time-to-peak of the agonist muscle. Methods.27 individuals with FA and 13 healthy controls (HC) performed the modified Functional Ataxia Rating Scale (mFARS), and goal-directed movements with the ankle. Dysmetria was quantified as position and time error during dorsiflexion. Results. FA individuals exhibited greater time but not position error than HC. Moreover, time error correlated with disease severity and was related to increased agonist EMG burst. Discussion. Temporal dysmetria is associated to functional capacity, likely due to altered activation of the agonist muscle.

Speech and Language Disorders in Friedreich Ataxia: Highlights on Phenomenology, Assessment, and Therapy

ommaso Schirinzi, Andrea Sancesario, Enrico Bertini, Enrico Castelli, Gessica Vasco. Cerebellum (2019). Doi:10.1007/s12311-019-01084-8

FRDA patients often present dysarthria, resulting from central and peripheral causes and additional primary language disorders. Speech disturbances have peculiar characteristics, although variable among patients, and progress along the disease course. Assessment relies on multiple but not specific clinical scales, some of which can also reflect the general severity of ataxia; classical instrumental investigations and novel technologies allow more accurate measurements of several speech parameters, which could found application as potential disease’s biomarkers. No successful treatments exist for communication disorders of FRDA patients; however, the tailored speech training or the non-invasive neuromodulation appear as the most reliable therapeutic options to be validate in future trials.

Induced pluripotent stem cell-derived primary proprioceptive neurons as Friedreich ataxia cell model

Chiara Dionisi, Myriam Rai, Marine Chazalon, Serge Schiffmann, Massimo Pandolfo, bioRxiv 829358 doi:10.1101/829358

We modified the dual-SMAD inhibition/WNT activation protocol, previously used to generate nociceptor-enriched cultures of primary sensory neurons from iPSCs, to favor instead the generation of proprioceptors. We succeeded in substantially enriching iPSC-derived primary sensory neuron cultures in proprioceptors, largely exceeding the proportion normally represented by these cells in dorsal root ganglia. We also showed that almost pure populations of proprioceptors can be purified from these cultures by fluorescence-activated cell sorting. Finally, we demonstrated that iPSCs from a FRDA patient can generate normal appearing proprioceptors but have subtle differentiation deficits and more limited survival.

Quantitative Proteomic and Network Analysis of Differentially Expressed Proteins in PBMC of Friedreich’s Ataxia (FRDA) Patients

Pathak D , Srivastava AK , Padma MV , Gulati S, Rajeswari MR; Front. Neurosci., 14 October 2019 doi:10.3389/fnins.2019.01054

In this study, comparative proteomic profiling of PBMC proteins from FRDA patients and age- and gender-matched healthy controls was done using 2D-Differential in-Gel Electrophoresis (2D-DIGE). Protein–protein interaction (PPI) was analyzed using BioGRID and STRING pathway analysis tools. Using biological variance analysis (BVA) and LC/MS, we found eight differentially expressed proteins with fold change ≥1.5; p ≤ 0.05. Based on their cellular function, the identified proteins showed a strong pathological role in neuroinflammation, cardiomyopathy, compromised glucose metabolism, and iron transport, which are the major clinical manifestations of FRDA. Protein–protein network analysis of differentially expressed proteins with frataxin further supports their involvement in the pathophysiology of FRDA. Considering their crucial role in the cardiac and neurological complications, respectively, the two down-regulated proteins, actin α cardiac muscle 1 (ACTC1) and pyruvate dehydrogenase E1 component subunit β (PDHE1), are suggested as potential prognostic markers for FRDA.

Evaluation of antibodies for western blot analysis of frataxin protein isoforms

Liwei Weng, Qingqing Wang, Sixiang Yu, Xiaolu Yang, David R. Lynch, Clementina Mesaros, Ian A. Blair, Journal of Immunological Methods, Volume 474, 2019, 112629, doi:10.1016/j.jim.2019.07.001.

Frataxin is the protein that is down-regulated in Friedreich ataxia (FRDA), an autosomal recessive genetic disease caused by an intronic GAA repeat expansion in intron-1 of the FXN gene. The GAA repeats result in epigenetic silencing of the FXN gene and reduced expression of the cytosolic full-length frataxin (1−210) protein. Full length frataxin translocates to the mitochondria, leading to formation of mature frataxin (81–210) formed by cleavage of the mitochondrial targeting sequence at K-80 of the full-length protein. There are currently no approved treatments for FRDA, although experimental approaches involving up-regulation or replacement of mature frataxin protein through numerous approaches are being tested. Many of the pre-clinical studies of these experimental approaches are conducted in mouse and monkey models as well as in human cell lines. Consequently, well-validated antibodies are required for use in western blot analysis to determine whether levels of various forms of frataxin have been increased. Here we examined the specificity of five commercially available anti-frataxin antibodies and determined whether they detect mature frataxin in mouse heart tissue. Four protein standards of monkey, human, and mouse frataxin as well as mouse heart tissue were examined using polyacrylamide gel electrophoresis (PAGE) in combination with western blot analysis. One antibody failed to detect any of the frataxin standards or endogenous frataxin in mouse heart tissue. Three of the antibodies detected a protein in mouse heart tissue that ran slightly faster on PAGE (at 23.4 kDa) to that predicted for full-length frataxin (23.9 kDa). One antibody detected all four frataxin standards as well as endogenous mouse mature frataxin in mouse tissue. Significantly, this antibody, which will be useful for monitoring mature frataxin levels in monkey, human, and mouse tissues, did not detect a protein in mouse heart tissue at 23.4 kDa. Therefore, antibodies detecting the immunoreactive protein at 23.4 kDa could be misleading when testing for the up-regulation of frataxin in animal models.

The first biallelic missense mutation in the FXN gene in a consanguineous Turkish family with Charcot-Marie-Tooth-like phenotype

YAyşe Candayan, Gulshan Yunisova, Arman Çakar, Hacer Durmuş, A. Nazlı Başak, Yeşim Parman, Esra Battaloğlu. Neurogenetics (2019). doi:10.1007/s10048-019-00594-1

To the best of our knowledge, this family represents the first FXN missense mutation in homozygosity and challenges the notion that missense mutations have not been reported yet due to their embryonic lethality. Furthermore, this finding poses an interesting genetic overlap between autosomal recessive CMT and FRDA that we believe may have important implications on understanding the pathogenesis of these neurological disorders.