Cross-regulation of [2Fe–2S] cluster synthesis by ferredoxin-2 and frataxin

Want, K., Gorny, H., Turki, E. et al. Cross-regulation of [2Fe–2S] cluster synthesis by ferredoxin-2 and frataxin. Nature (2025). doi: 10.1038/s41586-025-09822-1 

 Using an in-vitro-reconstituted human system, we show that any deviation from a close-to-equal amount of FXN and FDX2 downregulates Fe–S cluster synthesis. Structure–function investigation reveals that this is due to competition between FXN and FDX2 and their similar affinities for the same binding site on the NFS1–ISCU2 complex, with higher levels of FXN impairing the persulfide reductase activity of FDX2 and higher levels of FDX2 slowing the FXN-accelerated transfer of persulfide to ISCU2. We also find that FDX2 directly hinders persulfide generation and transfer to ISCU2 by interacting with the persulfide-carrying mobile loop of NFS1. We further show that knocking down the expression of FDX2 increases fly lifespan in a Drosophila model of Friedreich’s ataxia. Together, this work highlights a direct regulation of Fe–S cluster biosynthesis through antagonistic binding of FXN and FDX2, and suggests that decreasing FDX2 in the context of FXN deficiency in Friedreich’s ataxia might constitute a novel therapeutic axis.

Mutations in mitochondrial ferredoxin FDX2 suppress frataxin deficiency

Meisel, J.D., Joshi, P.R., Spelbring, A.N. et al. Mutations in mitochondrial ferredoxin FDX2 suppress frataxin deficiency. Nature (2025). doi:10.1038/s41586-025-09821-2 

We show that lowering levels of wild-type FDX2 through loss of one gene copy can ameliorate the growth of frataxin mutant C. elegans or the ataxia phenotype of a mouse model of Friedreich’s ataxia under normoxic conditions. These genetic and biochemical studies indicate that restoring the stoichiometric balance of frataxin and FDX2 through partial knockdown of FDX2 may be a potential therapy for Friedreich’s ataxia.

Eli Lilly (LLY) Completes Acquisition of Adverum Biotechnologies

Eli Lilly (LLY) Completes Acquisition of Adverum Biotechnologies. GuruFocus News 12/09/2025. 

This acquisition enhances Eli Lilly's portfolio, which also includes promising candidates for retinitis pigmentosa and Friedreich's ataxia.

Solid Biosciences Receives FDA Rare Pediatric Disease Designation for SGT-212 Dual Route of Administration Gene Therapy for Friedreich’s Ataxia

CHARLESTOWN, Mass., Dec. 01, 2025 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. today announced that it received Rare Pediatric Disease designation from the U.S. Food and Drug Administration (FDA) for SGT-212, the Company’s investigational gene therapy for Friedreich’s ataxia (FA). SGT-212 will deliver the full-length frataxin gene via dual routes of administration, utilizing both direct intradentate nucleus (IDN) and intravenous (IV) infusions, and was designed to promote restoration of therapeutic levels of the frataxin protein to address neurologic, cardiac and systemic clinical manifestations of FA.

Together with the Fast Track designation granted earlier this year, it recognizes our dual-route clinical approach for FALCON, our first-in-human trial, which is now screening participants, as an important first step in meeting an unmet need for FA. These designations are designed to help accelerate time to market and enhance engagement with the FDA. We look forward to continued collaboration with regulators to bring this therapy to patients as quickly as possible.

Enhancing the Objective Assessment of Friedreich Ataxia Severity: A Multiview IMU-Based Approach

Ranaweera K, Nguyen BA, Pathirana PN, Milne SC, Horne M, Delatycki MB, Corben LA. Enhancing the Objective Assessment of Friedreich Ataxia Severity: A Multiview IMU-Based Approach. Annu Int Conf IEEE Eng Med Biol Soc. 2025 Jul;2025:1-6. doi: 10.1109/EMBC58623.2025.11253596. PMID: 41335798. 

These findings indicate that multiview IMU-based systems can provide sensitive and reliable assessments of severity of ataxia in FRDA.Clinical relevance-This study presents a multiview IMU-based approach that can enhances the objective assessment of severity of ataxia in FRDA.

Reliable Objective Assessment of Friedreich Ataxia Through Isolation Forest-Based Anomaly Detection

Ranaweera K, Randeniya M, Pathirana PN, Milne SC, Horne M, Delatycki MB, Corben LA. Reliable Objective Assessment of Friedreich Ataxia Through Isolation Forest-Based Anomaly Detection. Annu Int Conf IEEE Eng Med Biol Soc. 2025 Jul;2025:1-6. doi: 10.1109/EMBC58623.2025.11253335. PMID: 41336277.

Clinical relevance- This study improves the reliability of objective Friedreich's ataxia assessments, providing clinicians with a more consistent and accurate tool for tracking disease progression and evaluating treatment effects.

A case of Friedreich Ataxia and left ventricular hypertrophy induced by FXN gene mutation

Zhou BY, Ren N, Zhang YY, Geng J. [A case of Friedreich Ataxia and left ventricular hypertrophy induced by FXN gene mutation]. Zhonghua Xin Xue Guan Bing Za Zhi. 2025 Nov 24;53(11):1271-1274. Chinese. doi: 10.3760/cma.j.cn112148-20250917-00659. PMID: 41287297.

 弗里德赖希共济失调（FRDA）是欧洲常见的常染色体隐性遗传疾病，但在中国较为罕见，目前国内尚无经基因诊断的FRDA病例报道。该文报道1例运动发育迟缓且步态不稳的男性患者，超声心动图检测到左心室肥厚，心脏磁共振成像显示左心室壁心肌多灶性钆对比剂延迟强化。基因检测显示FXN基因复合杂合突变：c.482+2T>A突变和第一内含子GAA三核苷酸序列异常扩增（8次和>66次重复），其中GAA拷贝数大于66次达到FRDA的致病性扩增阈值。. 

Friedreich ataxia (FRDA) is a common autosomal recessive disease in Europe, but it is rarer in China, and no genetically diagnosed FRDA cases have been reported in China. This article reported a male patient with delayed motor development and unstable gait, left ventricular hypertrophy was detected by echocardiography, and cardiac magnetic resonance imaging showed delayed enhancement of myocardial multifocal gadolinium contrast agent in the left ventricular wall. Genetic testing revealed complex heterozygous mutations in the FXN gene: c.482+2 T>A mutation and abnormal amplification of the first intron GAA trinucleotide sequence (8 and >66 replicates), where the GAA copy number was greater than 66 to reach the pathogenic amplification threshold of the FRDA.

Survival in Brazilian Patients with Friedreich´s Ataxia

Machado DS, Silveira C, Vinagre AM, Rezende TJR, Dogini D, Martinez ARM, França MJC. Survival in Brazilian Patients with Friedreich´s Ataxia. Cerebellum. 2025 Nov 22;24(6):182. doi: 10.1007/s12311-025-01936-6. PMID: 41273607.

Shorter life expectancy was found: in men relative to women (Mean age: 54.0 yo vs. 56.8 yo, p = 0.03), in patients with classical relative to late-onset (Mean age: 52.2 yo vs. 71.0 yo, p < 0.01) and in patients with cardiomyopathy relative to those without it (Mean age: 50.8 yo vs. 65.0 yo, p < 0.01). FRDA impacts life expectancy and death is primarily from cardiac and pulmonary causes. Male sex, early onset and presence of cardiomyopathy are negative survival prognostic markers.

NFS1, together with FXN, protects cells from ferroptosis and DNA damage in diffuse large B-cell lymphoma

Shi X, Zhao Y, Gao HY, Yang W, Liao J, Wang HH, Wang XT, Yan W. NFS1, together with FXN, protects cells from ferroptosis and DNA damage in diffuse large B-cell lymphoma. Redox Biol. 2025 Nov;87:103878. doi: 10.1016/j.redox.2025.103878. Epub 2025 Sep 23. PMID: 41005206; PMCID: PMC12505007.

We demonstrated that ISC-related proteins NFS1 and FXN protect DLBCL cells from ferroptosis and DNA damage, thus exhibiting an essential role in DLBCL progression.

Partial Bypass of Frataxin Deficiency by ISCU M141I Restores Cytosolic and Nuclear Fe-S Cluster Assembly

Mosbach V, Maio N, Diedhiou N, Hennick A, Dall'Agnol L, Reutenauer L, Marczak L, Birling MC, Eisenmann A, Martelli A, Hélène PH. Partial Bypass of Frataxin Deficiency by ISCU M141I Restores Cytosolic and Nuclear Fe-S Cluster Assembly. bioRxiv [Preprint]. 2025 Sep 6:2025.09.03.673074. doi: 10.1101/2025.09.03.673074. PMID: 41019637; PMCID: PMC12466782. 

 Altogether, our results reveal a previously unrecognized compartment-specific rescue of Fe-S cluster dependent processes by the ISCU M141I variant in mammalian cells, raising for the first time the possibility of compartmental regulation of Fe-S cluster biogenesis.