Trinucleotide repeat analysis of Huntington's disease gene in Singapore.
نویسندگان
چکیده
INTRODUCTION Huntington's disease (HD) is an inherited neurodegenerative disorder characterised by chorea and progressive dementia. The mutation causing the disease has been identified as an unstable expansion of a trinucleotide (CAG)n. We have assessed the (CAG)n repeats in the patients and controls in our population. MATERIALS AND METHODS Polymerase chain reactions (PCRs) for the repeat region were carried out for 116 individuals: 10 were asymptomatic at-risk members from 5 families; 53 symptomatic patients from various hospitals; and 53 normal unrelated Singaporeans. Estimation of the number of repeats was based on Metaphor gel electrophoresis, sizing using the GeneScan on ABI 310 Genetic Analyzer, and sequencing using the same equipment. RESULTS Metaphor gel sizing generally gives an over-estimation, and GeneScan gives an under-estimation of repeat numbers compared with sequencing which is the gold standard. Of the 63 patients and family members tested, 25 had one expanded allele of 40 to 54 CAG repeats and the other allele in the normal range of 15 to 30 repeats. One patient had an allele in the intermediate range (38). CONCLUSION The range of CAG repeats in the normal and HD alleles in our population is similar to those reported elsewhere. An accurate sizing can only be obtained with sequencing. For allele sizes in the intermediate range (37-40), sequencing should be carried out to confirm the carrier status of a patient.
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1 Caine ED, Shoulson T. Psychiatric syndrome in Huntington's disease. AmJPsychiatry 1983; 140:728-33. 2 Seeman P, Niznik HB, Guan HC, et al. Link between DI and D2 dopamine receptor is reduced in schizophrenia and Huntington's disease brain. Proc Natl Acad Sci USA 1989; 86:10156-60. 3 MacDonald ME, Ambrose CM, Duyao MP, et al. A novel gene containing a trinucleotide repeat that is expanded and ...
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OBJECTIVE Huntington's disease (HD) has been reported to occur rarely in black patients. A new genetic variant- Huntington's disease-like 2 (HDL2)--occurring more frequently in blacks, has recently been described. The absence of an expanded trinucleotide repeat at the chromosome 4 HD locus was previously regarded as a way of excluding classic HD. The objective of this paper is to describe a num...
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عنوان ژورنال:
- Annals of the Academy of Medicine, Singapore
دوره 30 2 شماره
صفحات -
تاریخ انتشار 2001