New Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome cases are caused by the presence of a nonsense variant in compound heterozygosity with the pathogenic repeat expansion in the RFC1 gene.

Clinical genetics 2023 Feb

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The biallelic pathogenic repeat (AAGGG)400-2000 intronic expansion in the RFC1 gene has been recently described as the cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) and as a major cause of late-onset ataxia. Since then, many heterozygous carriers have been identified, with an estimated allele frequency of 0.7% to 4% in the healthy population. Here, we describe in two affected CANVAS sisters the presence of the nonsense c.724C > T p.(Arg242*) variant in compound heterozygosity with the pathogenic repeat expansion in the RFC1 gene. Further RNA analysis demonstrated a reduced expression of the p.Arg242* allele in patients confirming an efficient nonsense-mediated mRNA decay. We also highlight the importance of considering the sequencing of the RFC1 gene for the diagnosis, especially in patients with CANVAS diagnosis carriers of the AAGGG repeat expansion. © 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Citation

Ana Arteche-López, Almudena Avila-Fernandez, Alejandra Damian, Emma Soengas-Gonda, Rubén Pérez de la Fuente, Patricia Ramos Gómez, Jesús Gallego Merlo, Laura Horcajada Burgos, Carlos Cemillán Fernández, Jose Miguel Lezana Rosales, Juan Francisco González Martínez, Juan Francisco Quesada-Espinosa, Marta Corton, Maria Paz Guerrero-Molina. New Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome cases are caused by the presence of a nonsense variant in compound heterozygosity with the pathogenic repeat expansion in the RFC1 gene. Clinical genetics. 2023 Feb;103(2):236-241