The Natural History Study and Biomarker Collection of the Clinical Research Consortium for the Study of Cerebellar Ataxia (CRC-SCA).

Hereditary ataxias are progressive neurodegenerative disorders primarily affecting the cerebellum. Since 2009, the Clinical Research Consortium for the Study of Cerebellar Ataxias (CRC-SCA) has studied the natural history of common types of spinocerebellar ataxias (SCAs). The CRC-SCA is a 17-site academic collaboration supported by the National Ataxia Foundation. In 2024, the CRC-SCA expanded its scope by incorporating newly identified late-onset ataxias, including repeat expansion mutations in RFC1 and FGF14 causing Cerebellar Ataxia with Neuropathy and Vestibular Areflexia Syndrome (CANVAS) and SCA27B, respectively. These ongoing efforts have enriched the understanding of disease progression and facilitated access to biofluid and neuroimaging data for biomarker discovery, setting the stage for therapeutic development in hereditary ataxias. The CRC-SCA's natural history study and biomarker collection have validated several clinical outcome assessments (COAs) to capture important aspects of hereditary ataxias. We have also developed new COAs for cognitive and patient-reported outcome measures. A key component of the study includes biofluid collection-cerebrospinal fluid, plasma, and serum-to identify molecular biomarkers for disease progression and therapeutic response. Additionally, an incorporated magnetic resonance imaging (MRI) substudy provides critical imaging biomarkers, enhancing our ability to track macro- and microstructural, chemical and functional changes in the cerebellum and relate these to clinical presentations. The comprehensive, longitudinal dataset comprising COAs, biofluid biomarkers, and neuroimaging enhances clinical trial readiness in the field and accelerates therapeutic advancements for hereditary ataxias. This review highlights the collective efforts of CRC-SCA, details the study protocol, and emphasizes the integrity and specificity of the collected data elements.