David G Anderson1,2, Aline Ferreira-Correia3, Filipe B Rodrigues4,5,6, N Ahmad Aziz7, Jonathan Carr8, Edward J Wild4, Russell L Margolis9, Amanda Krause2. 1. The University of the Witwatersrand Donald Gordon Medical Centre Neurology Johannesburg South Africa. 2. Division of Human Genetics National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand Johannesburg South Africa. 3. Department of Psychology School of Human and Community Development, University of the Witwatersrand. Johannesburg South Africa. 4. UCL Huntington's Disease Centre University College London UK. 5. Clinical Pharmacology Unit Instituto de Medicina Molecular Portugal. 6. Laboratory of Clinical Pharmacology and Therapeutics University of Lisbon Portugal. 7. German Center for Neurodegenerative Diseases (DZNE) Bonn Germany. 8. Division of Neurology, Department of Medicine University of Stellenbosch Cape Town South Africa. 9. Departments of Psychiatry and Neurology, Program in Cellular and Molecular Medicine Johns Hopkins University School of Medicine Baltimore MD USA.
Abstract
BACKGROUND: Huntington's disease like 2 (HDL2) is the most common Huntington's disease (HD) phenocopy in many countries and described as the phenocopy with the greatest resemblance to HD. The current clinical description of HDL2 is based on retrospective data. It is unknown whether HDL2 has clinical features that distinguish it from HD. OBJECTIVE: To describe the HDL2 phenotype and compare it to HD systematically. METHODS: A blinded cross-sectional design was used to compare the HDL2 (n = 15) and HD (n = 13) phenotypes. African ancestry participants underwent assessments, including the Unified Huntington's Disease Rating Scale (UHDRS). The UHDRS motor component was video recorded and evaluated by blinded experts and the inter-rater reliability calculated. RESULTS: Both groups were homogeneous in terms of demographics and disease characteristics. However, HDL2 patients presented three years earlier with more prominent dysarthria and dystonia. Raters could not distinguish between the two diseases with a high level of agreement. No significant differences in the TMS between HDL2 and HD were found. In both disorders, disease duration correlated with motor scores, with the exception of chorea. Psychiatric and cognitive scores were not significantly different between the groups. CONCLUSIONS: The HDL2 phenotype is similar to HD and is initially characterized by dementia, chorea, and oculomotor abnormalities, progressing to a rigid and bradykinetic state, suggesting the UHDRS is useful to monitor disease progression in HDL2. Although HDL2 patients scored higher on some UHDRS domains, this did not differentiate between the two diseases; it may however be emerging evidence of HDL2 having a more severe clinical phenotype.
BACKGROUND: Huntington's disease like 2 (HDL2) is the most common Huntington's disease (HD) phenocopy in many countries and described as the phenocopy with the greatest resemblance to HD. The current clinical description of HDL2 is based on retrospective data. It is unknown whether HDL2 has clinical features that distinguish it from HD. OBJECTIVE: To describe the HDL2 phenotype and compare it to HD systematically. METHODS: A blinded cross-sectional design was used to compare the HDL2 (n = 15) and HD (n = 13) phenotypes. African ancestry participants underwent assessments, including the Unified Huntington's Disease Rating Scale (UHDRS). The UHDRS motor component was video recorded and evaluated by blinded experts and the inter-rater reliability calculated. RESULTS: Both groups were homogeneous in terms of demographics and disease characteristics. However, HDL2 patients presented three years earlier with more prominent dysarthria and dystonia. Raters could not distinguish between the two diseases with a high level of agreement. No significant differences in the TMS between HDL2 and HD were found. In both disorders, disease duration correlated with motor scores, with the exception of chorea. Psychiatric and cognitive scores were not significantly different between the groups. CONCLUSIONS: The HDL2 phenotype is similar to HD and is initially characterized by dementia, chorea, and oculomotor abnormalities, progressing to a rigid and bradykinetic state, suggesting the UHDRS is useful to monitor disease progression in HDL2. Although HDL2 patients scored higher on some UHDRS domains, this did not differentiate between the two diseases; it may however be emerging evidence of HDL2 having a more severe clinical phenotype.
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