Following PRISMA-ScR guidelines, we conducted a scoping review of PubMed and complementary sources (2010–2025) to map and describe the current landscape of genetic, imaging, fluid, electrophysiological, and digital biomarkers across the most prevalent hereditary ataxias, including SCA1, SCA2, SCA3, SCA6, SCA7, SCA17, SCA27B, dentatorubral–pallidoluysian atrophy (DRPLA), Friedreich’s ataxia (FRDA), RFC1-related ataxia (CANVAS), SPG7, and fragile X-associated tremor/ataxia syndrome (FXTAS). The gene discussed is CACNA1A; the disease is Rare hereditary ataxia.