Huntington's disease in Ecuador: Genetic evidence, clinical gaps, and national priorities

Huntington's disease is an autosomal dominant neurodegenerative disorder caused by an expanded CAG repeat in exon 1 of the huntingtin gene (HTT). Evidence from Ecuador remains dispersed across original articles, university theses, and clinical or rehabilitation reports. This narrative review critically integrates the Ecuadorian evidence and places it within current international genetic, clinical, and therapeutic knowledge. Searches of biomedical databases, regional indexes, institutional repositories, and Ecuadorian journals through August 2026 identified two principal molecular cohorts, related theses, and complementary clinical publications. The largest study included 412 participants and uniquely combined HTT CAG-repeat analysis with ethnic-group comparisons and ancestry inference. It demonstrated heterogeneous allele distributions among Kichwa, Mestizo, and Afro-Ecuadorian participants, but its sample was not nationally representative and cannot establish prevalence. Earlier family-based work documented pathogenic expansions, presymptomatic carriers, anticipation, and a juvenile presentation. Across studies, interpretation is limited by overlapping samples, inconsistent historical allele terminology, low-resolution sizing in some series, small clinical cohorts, and the absence of national epidemiological or longitudinal data. International evidence published since the Ecuadorian studies has reframed the disease as a process driven largely by somatic expansion of the uninterrupted CAG tract in vulnerable neurons. Therapeutic development has produced contrasting signals: an intrastriatal gene therapy has been reported to slow progression relative to external controls, whereas an intrathecal antisense huntingtin-lowering program was discontinued after failing to show clinical benefit. Ecuador now needs a protected registry, standardized molecular testing with high-resolution sizing and genetic counseling, multidisciplinary clinical pathways, and research incorporating uninterrupted CAG length, sequence interruptions, somatic expansion, modifier genes, and prospective phenotyping aligned with international staging frameworks. Existing evidence establishes a substantive national genetic foundation while exposing inequities in access and unresolved epidemiological questions that must be addressed before Ecuadorian families can benefit from emerging disease-modifying therapies.