Nationwide survey and epidemiology of Huntington's disease in Hungary.

BACKGROUND: Huntington's disease (HD) is a rare, autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion in the HTT gene. Despite its defined genetic basis, epidemiological coverage remains heterogeneous across Europe. OBJECTIVE: To assess the temporal and regional distribution of genetically confirmed HD cases in Hungary (2003-2021) and the impact of healthcare accessibility and the COVID-19 pandemic on diagnostic activity. METHODS: We analyzed 480 genetically confirmed patients (217 males, 263 females) with pathogenic HTT expansions (>36 CAG repeats). Diagnostic incidence (per 100,000 person-years) and prevalence (per 100,000 population) were calculated using national demographic data. Associations between CAG repeat length and age at onset were examined, and spatial analyses assessed regional distribution relative to specialized centers. RESULTS: Mean annual diagnostic incidence was 0.32 per 100,000 person-years and prevalence 4.73 per 100,000. Median CAG repeat length was 44 (IQR: 41-47), with median age at onset of 45 years, showing an inverse correlation (R² = 0.41, p < 0.0001). Diagnostic incidence was within the lower-to-mid European range, while prevalence was comparable to Western Europe. Regional disparities were evident, with 65% of cases within 70 km of tertiary centers. Diagnostic activity declined by ∼25% during the pandemic. CONCLUSIONS: Although the genetic and clinical characteristics of Huntington's disease in Hungary are comparable to other European populations, the observed epidemiological patterns appear to be influenced by healthcare accessibility. Inequitable access to specialized neurological services may affect case identification and diagnostic timing, and is likely to contribute to differences in epidemiological estimates in rare neurodegenerative disorders.