Clinical trial NCT04594590: Natural History Study of SLC25A46 Mutation-related Mitochondriopathy
Official title: A Natural History Study of Neurodegeneration and Optic Atrophy Caused by SLC25A46 Mutations in Pediatric and Adult Patients
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Neurodegenerative Disease, Hereditary
Mitochondrial Diseases
Optic Atrophy
Keywords: Neurodegeneration
Mitochondrial disease
Optic atrophy
SLC25A46
Mitochondrial fission
Lead sponsor: State University of New York at Buffalo
Sponsor class: OTHER
Collaborators: name: Hadley Jo Foundation
First posted: 2020-10-20
Enrollment: 9
Sex: ALL
Minimum age (years): 0
Maximum age (years): 65
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_ONLY
Time perspective: OTHER
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Primary care clinic

Brief summary: The purpose of the study is to systematically characterize the clinical course of the progressive neuropathy and optic atrophy observe in pediatric and adult patients with biallelic mutations in the solute carrier family 25 member 46 (SLC25A46) gene.

Detailed description: The number of mitochondria in the cell is dynamic and is regulated by two opposite processes, namely fission and fusion. Proteins in both the inner mitochondrial membrane (IMM) and the outer mitochondrial membrane (OMM) are involved in mediating these two processes, including OPA1, MFN2 and SLC25A46. Recent work by the investigators as well as other research groups has shown that mutations in SLC25A46 cause abnormal mitochondrial fusion, leading to optic nerve atrophy, axonal peripheral neuropathy and cerebellar degeneration by interfering with mitochondrial fission. Recently, the investigators have used CRISPR genome editing to generate a global Slc25a46 KO mouse model with complete loss of SLC25A46 in all tissues (PMID: 28934388). Similar to patients with biallelic mutations in SLC25A46, these mice exhibit severe ataxia, optic atrophy, peripheral neuropathy related to axonal degeneration, and demyelination due to mitochondrial hyperfusion and defective energy production. In these mice, histological staining revealed a hypotrophic cerebellum with a severe loss of Purkinje cells (PCs) and/or stunted PC dendrites while electron microscopy revealed enlarged mitochondria with swollen cristae and other abnormal morphologies in PC dendrites and sciatic nerves. Furthermore, in primary culture, PCs from these mice exhibited abnormal mitochondrial distribution and movement.

These findings provide compelling evidence indicating that SLC25A46 plays an important role in the regulation of mitochondrial dynamics-including fusion/fission, distribution, and movement, as well as the maintenance of cristae architecture-and that loss of SLC25A46 function has a particularly severe effect on a distinct subset of neuron types with long axonal processes. More recently, the investigators have shown that AAV-based gene therapy can produce dramatic improvements in their Slc25a46 mutant mouse model (PMID: 31943007). These studies in the Slc25a46 mouse model provide the foundation for uncovering the mechanism whereby these this gene causes disease in humans, as well as lay the groundwork for the possible use of gene therapy to ameliorate the disease phenotype in patients.

However, despite this progress, there remains only a handful of studies published on Slc25a46 and the consequences of loss of Slc25a46 function in humans. Given that human SLC25A46-associated phenotypes overlap substantially with DOA and CMT2A, further study of this rare condition presents an opportunity not only to better understand and treat SLC25A46-related disease, but also to elucidate the broader mechanistic link between neurodegeneration and abnormal mitochondrial dynamics. Thus, in order to better understand the clinical manifestations of SLC25A46-related disease and to help lay the groundwork for eventual clinical trials of gene therapy or drug-based treatments, the investigators propose this natural history study of pediatric as well as adult patients with biallelic mutations in the SLC25A46 gene.

Eligibility criteria: Inclusion Criteria:

* Patients who are clinically diagnosed with biallelic mutations in the SLC25A46 gene
* Male and female patients from 2 to 65 years of age
* Patients who have consented to the study
* In the case of a deceased patient whose parent(s) and/or legal guardian(s) have provided informed consent for study participation, the investigators will review the patient's medical records to determine study eligibility.

Exclusion Criteria:

* Significant postnatal complications or congenital anomalies that are not known to be associated with SLC25A46 dysfunction
* Patient has received any experimental treatment for SLC25A46 dysfunction within the 6 months prior to enrollment, or is expected to receive any such therapy during the study period

Primary outcomes:
measure: Custom Medical History Questionnaire for Patients with SLC25A46 Mutation-related Mitochondriopathy
timeFrame: 3 years
measure: Retrospective examination of the medical records of patients with SLC25A46 Mutation-related Mitochondriopathy
timeFrame: 3 years
measure: Eye assessments to evaluate ocular health
timeFrame: 3 years
measure: Growth and development (height)
timeFrame: 3 years
measure: Growth and development (weight)
timeFrame: 3 years
measure: Growth and development (BMI)
timeFrame: 3 years
Secondary outcomes:
Other outcomes:
Locations:
city: Buffalo
country: United States
facility: UBMD Pediatrics
state: New York
Study officials:
affiliation: State University of New York at Buffalo
name: Taosheng Huang
role: PRINCIPAL_INVESTIGATOR
References:
citation: Abrams AJ, Hufnagel RB, Rebelo A, Zanna C, Patel N, Gonzalez MA, Campeanu IJ, Griffin LB, Groenewald S, Strickland AV, Tao F, Speziani F, Abreu L, Schule R, Caporali L, La Morgia C, Maresca A, Liguori R, Lodi R, Ahmed ZM, Sund KL, Wang X, Krueger LA, Peng Y, Prada CE, Prows CA, Schorry EK, Antonellis A, Zimmerman HH, Abdul-Rahman OA, Yang Y, Downes SM, Prince J, Fontanesi F, Barrientos A, Nemeth AH, Carelli V, Huang T, Zuchner S, Dallman JE. Mutations in SLC25A46, encoding a UGO1-like protein, cause an optic atrophy spectrum disorder. Nat Genet. 2015 Aug;47(8):926-32. doi: 10.1038/ng.3354. Epub 2015 Jul 13.
citation: Li Z, Peng Y, Hufnagel RB, Hu YC, Zhao C, Queme LF, Khuchua Z, Driver AM, Dong F, Lu QR, Lindquist DM, Jankowski MP, Stottmann RW, Kao WWY, Huang T. Loss of SLC25A46 causes neurodegeneration by affecting mitochondrial dynamics and energy production in mice. Hum Mol Genet. 2017 Oct 1;26(19):3776-3791. doi: 10.1093/hmg/ddx262.
citation: Yang L, Slone J, Li Z, Lou X, Hu YC, Queme LF, Jankowski MP, Huang T. Systemic administration of AAV-Slc25a46 mitigates mitochondrial neuropathy in Slc25a46-/- mice. Hum Mol Genet. 2020 Mar 13;29(4):649-661. doi: 10.1093/hmg/ddz277.
citation: Qiu K, Zou W, Fang H, Hao M, Mehta K, Tian Z, Guan JL, Zhang K, Huang T, Diao J. Light-activated mitochondrial fission through optogenetic control of mitochondria-lysosome contacts. Nat Commun. 2022 Jul 25;13(1):4303. doi: 10.1038/s41467-022-31970-5.
citation: Zou W, Chen Q, Slone J, Yang L, Lou X, Diao J, Huang T. Nanoscopic quantification of sub-mitochondrial morphology, mitophagy and mitochondrial dynamics in living cells derived from patients with mitochondrial diseases. J Nanobiotechnology. 2021 May 13;19(1):136. doi: 10.1186/s12951-021-00882-9.