Objective: To provide a comprehensive description of the first clinical case of SCAR10 diagnosed in Mexico.

Background: The autosomal recessive spinocerebellar ataxia type 10 is a rare neurodegenerative disorder mainly associated with nystagmus and cognitive impairment. Also, seizures have been observed in some patients. We present here a sporadic case of degenerative ataxia classified as a new ARCA, its evolution and definite diagnosis.

Method: A clinical protocol was applied to classify the entity through symptomatology, laboratory, and imaging analysis. Once diagnosed as non-Friedreich recessive ataxia, next-generation sequencing was performed on DNA extracted from peripheral blood under informed consent. The coding and splice regions on both sides of each exon of 4816 genes were analyzed. Capture technology was followed by NGS on MiSeq or NextSeq equipment, bioinformatic analysis, and annotation of variants with the Sophia GeneticsDMMv.5.1.2 platform before reviewing international databases and literature.

Results: A female patient from Toluca, State of Mexico, without a significant family history, preeclampsia at 21y, a loss of consciousness with head trauma at 28y. AAO was estimated at 25y with slight gait instability, dysarthria, headache, nausea, sadness, situational and reactive anxiety. A mild cognitive deterioration with dysexecutive signs so as moderate/severe cerebellar atrophy was then identified at our Institute. The EEG was normal. Frequent diplopia, horizontal and downbeat nystagmus, slow and hypermetric saccades, and vertigo with dehiscence of left-supSCC responded to acetylleucine. A Q10 treatment was interrupted for intolerance and the patient benefits from a quarterly treatment with B complex. Also, bilateral eyelid ptosis, scanned speech, dysmetria/dysdiadochokinesia, and pyramidal signs are slowly worsening. SARA score was 13 after 8y of evolution. A new pathogenic variant was identified in a homozygous state in the ANO10 gene that causes a premature stop codon in the protein.

Conclusion: This patient shows a clinical presentation of SCAR10 concordant with other case reports. Consanguinity in parents was negated but they both come from the same region; a discrete scanned language was noticed in the father. It is extremely important to report and follow these cases to understand mechanisms and to propose better therapeutic options.

References: 1. Nieto A, Pérez-Flores J, Corral-Juan M, Matilla-Dueñas A, Martínez-Burgallo F, Montón F. Cognitive characterization of SCAR10 caused by a homozygous c.132dupA mutation in the ANO10 gene. Neurocase. 2019;25(5):195-201. doi:10.1080/13554794.2019.1655064 2. Nanetti, L., Sarto, E., Castaldo, A., Magri, S., Mongelli, A., Rossi Sebastiano, D., Canafoglia, L., Grisoli, M., Malaguti, C., Rivieri, F., D’Amico, M. C., Di Bella, D., Franceschetti, S., Mariotti, C., & Taroni, F. (2019). ANO10 mutational screening in recessive ataxia: genetic findings and refinement of the clinical phenotype. Journal of neurology, 266(2), 378–385. https://doi.org/10.1007/s00415-018-9141-z

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MDS Abstracts - https://www.mdsabstracts.org/abstract/autosomal-recessive-spinocerebellar-ataxia-type-10-a-case-report-in-mexico/