Identification of an expanded CAG repeat in the Huntington's disease gene (IT15) in a family reported to have benign hereditary chorea

• Published in: Journal of medical genetics Vol. 30; no. 12; pp. 1012 - 1013
• Main Authors: MacMillan, J C, Morrison, P J, Nevin, N C, Shaw, D J, Harper, P S, Quarrell, O W, Snell, R G
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.12.1993; BMJ; BMJ Publishing Group LTD
• Subjects: Adult; Aged; Aged, 80 and over; Alleles; Biological and medical sciences; Chorea - diagnosis; Chorea - genetics; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; diagnosis; Diagnosis, Differential; Female; genes; Humans; Huntington Disease - diagnosis; Huntington Disease - genetics; Huntington's chorea; IT15 gene; Male; man; Medical sciences; Middle Aged; Neurology; Oligodeoxyribonucleotides - genetics; Pedigree; Repetitive Sequences, Nucleic Acid; Human; Nervous system diseases; Nucleotide sequence; Family study; Repeated sequence; Chorea; Cerebral disorder; Involuntary movement; Genetic disease; Central nervous system disease; Neurological disorder; Molecular biology; Extrapyramidal syndrome
• ISSN: 0022-2593; 1468-6244; 1468-6244
• DOI: 10.1136/jmg.30.12.1012

Benign hereditary chorea (BHC) is a rare autosomal dominant disorder characterised by the onset of non-progressive chorea in childhood and the absence of cognitive impairment. Using primers flanking the (CAG)n repeat in IT15, expansion of which is associated with HD, we have detected an abnormal PCR product in four affected members from one family where affected subjects were originally reported to have BHC. The expanded allele contains 38 repeats in the affected parent and this undergoes further enlargement to 39 and 45 repeats in the two affected offspring. We conclude that the diagnostic criteria for BHC should include a normal result from analysis for the (CAG)n expansion identified in HD.