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I-Hui Lee, MD; Bing-Wen Soong, MD, PhD; Yi-Chun Lu, BS; Yue-Cune Chang, PhD

Arch Neurol. 2001;58:1905-1908.

Background  Dentatorubropallidoluysian atrophy (DRPLA) is a rare, autosomal dominant neurodegenerative disease characterized by a range of clinical manifestations, including cerebellar ataxia, epilepsy, myoclonus, choreoathetosis, and dementia. Outside the Japanese population, the prevalence is extremely low worldwide. The reason for different ethnic prevalences of DRPLA is unclear. A previous assumption was that large normal alleles contribute to generation of expanded alleles and the relative frequencies of DRPLA.

Objectives  To describe the clinical, radiological, and genetic features of the first reported Chinese family with DRPLA, to our knowledge, and to compare the size distribution of normal alleles at the DRPLA locus in healthy Chinese individuals with that of other ethnic groups.

Patients and Methods  Of 80 Chinese kindreds with autosomally dominant spinocerebellar ataxias, 1 pedigree with 2 affected patients was found by polymerase chain reaction to carry the characteristic DRPLA mutation. The allele frequencies of different CAG repeat lengths at the DRPLA locus in 225 healthy Chinese individuals were also analyzed and compared with Japanese, white, and African American distributions.

Results  The clinical presentations of the 2 Chinese patients affected with DRPLA are similar to those described in Japanese patients, except that the affected father exhibited myoclonus but not chorea. Although the normal DRPLA allele size is distributed similarly in Chinese and Japanese populations, DRPLA in Chinese individuals is rare. Thus far, to our knowledge, only 1 intermediate-sized allele containing more than 30 CAG repeats has been reported among healthy Chinese individuals, in contrast to 3 among Japanese populations.

Conclusion  The ethnic prevalence of DRPLA seems to be correlated with the prevalence of intermediate-sized alleles in individual populations.

From The Neurological Institute, Taipei Veterans General Hospital (Drs Lee and Soong and Ms Lu), Department of Neurology, National Yang-Ming University School of Medicine (Dr Soong), and Department of Mathematics, Tamkang University (Dr Chang), Taipei, Taiwan, Republic of China.

Corresponding author and reprints: Bing-Wen Soong, MD, PhD, The Neurological Institute, Taipei Veterans General Hospital, No. 201, Section 2, Shih-Pai Rd, Taipei, Taiwan 112, Republic of China (e-mail: bwsoong{at}vghtpe.gov.tw).

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