Enlighten
Research publications by members of the University of Glasgow
home > services > Enlighten

Very large (CAG)(n) DNA repeat expansions in the sperm of two spinocerebellar ataxia type 7 males

Monckton, D.G., Cayuela, M.L., Gould, F.K., Brock, G.J.R., de Silva, R., and Ashizawa, T. (1999) Very large (CAG)(n) DNA repeat expansions in the sperm of two spinocerebellar ataxia type 7 males. Human Molecular Genetics, 8 (13). 2473 -2478. ISSN 0964-6906

Full text not currently available from Enlighten.

Publisher's URL: http://hmg.oupjournals.org/cgi/reprint/8/13/2473.pdf

Abstract

Genetic anticipation, i.e. increasing disease severity and decreasing age of onset from one generation to the next, is observed in a number of diseases, including myotonic dystrophy type 1, Huntington's disease and several of the spinocerebellar ataxias. All of these disorders are associated with the expansion of a trinucleotide repeat and array length is positively correlated with disease severity and inversely correlated with the age of onset. The expanded repeat is highly unstable and continues to expand from one generation to the next, providing a molecular explanation for anticipation. Spinocerebellar ataxia type 7 (SCA7) is one of the latest additions to the list of triplet repeat diseases and is distinct from the other SCAs in that it is accompanied by retinal degeneration. Pedigree analyses have previously revealed that the SCA7 repeat is highly unstable and liable to expand, in particular when transmitted by a male. Surprisingly, though, an under-representation of male transmission has also been reported. We now demonstrate directly by single molecule analyses that the expanded repeat is extraordinarily unstable in the male germline and biased toward massive increases. Nearly all of the mutant sperm of two SCA7 males contain alleles that are so large that most of the affected offspring would at best have a severe infantile form of the disease. Indeed, the gross under-representation of such very large expanded alleles in patients suggests that a significant proportion of such alleles might be associated with embryonic lethality or dysfunctional sperm.

Item Type:Article
Status:Published
Refereed:Yes
Glasgow Author(s):Monckton, Prof Darren
Authors: Monckton, D.G., Cayuela, M.L., Gould, F.K., Brock, G.J.R., de Silva, R., and Ashizawa, T.
Subjects:Q Science > QH Natural history > QH426 Genetics
College/School:College of Medical Veterinary and Life Sciences
Journal Name:Human Molecular Genetics
ISSN:0964-6906

University Staff: Request a correction | Enlighten Editors: Update this record