Late-onset Huntington disease with intermediate CAG repeats: true or false?
Huntington disease (HD) is a neurodegenerative disorder associated with an expanded CAG trinucleotide repeat length in the huntingtin gene. 'Intermediate alleles' with 27 to 35 CAG repeats generally do not cause HD but are unstable upon germ-line transmission. Insights in CAG repeat mosaicism and enhanced trinucleotide expansion in postmitotic neurons indicate that in the intermediate range, other factors than the CAG repeat length in diagnostic tests have to be considered. Here, we report two patients with mild, late onset HD and an intermediate repeat allele. The authors anticipate that intermediate repeats can cause late-onset HD due to disease modifiers and may be more common than previously stated.
Department of Neurology H2-237, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands.
Justus L
JL
Groen
Rob M A
RM
de Bie
Elisabeth M J
EM
Foncke
Raymund A C
RA
Roos
Klaus L
KL
Leenders
Marina A J
MA
Tijssen
D017668:Age of Onset; D000368:Aged; D000483:Alleles; D001921:Brain / Q000503:physiopathology*; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics; D005820:Genetic Testing; D006801:Humans; D006816:Huntington Disease / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology*; D008297:Male; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*