Current Status of Huntington's Disease in Korea: A Nationwide Survey and National Registry Analysis

Objective Huntington's disease (HD) is a rare neurological disorder, and its current status in Korea is not well investigated. This study aims to determine the prevalence and incidence of HD and to investigate the clinical features of HD patients in Korea. Methods We estimated the crude prevalence and annual incidence of HD based on the databases of the Rare Diseases Registry (RDR) and the National Health Insurance (NHI). The clinical data of genetically confirmed HD patients was collected from 10 referral hospitals and analyzed. Results The mean calculated annual incidence was 0.06 cases per 100,000 persons, and the mean calculated prevalence was 0.38 based on the NHI database. The estimated crude prevalence based on the RDR was 0.41. Of the sixty-eight HD patients recruited, the mean age of onset was 44.16 +/- 14.08 years and chorea was most frequently reported as the initial symptom and chief complaint. The mean CAG repeat number of the expanded allele was 44.7 +/- 4.8 and correlated inversely with the age of onset (p < 0.001). About two-thirds of the patients have a positive family history, and HD patients without positive family history showed a delay in onset of initial symptoms, a prolonged interval between initial symptom onset and genetic diagnosis and a delay in the age of genetic diagnosis. Conclusions To the best of our knowledge, this is the first study to estimate the prevalence and incidence of HD in Korea and the largest HD series in the Asian population. Our analyses might be useful for further studies and large- scale investigations in HD patients.