Moderate instability of the trinucleotide repeat in spino bulbar muscular atrophy

Increased length of a protein-coding CAG repeat within the androgen receptor gene appears to be the only type of mutation responsible for spino-bulbal muscular atrophy (SBMA or Kennedy disease). We have analysed a large 4-generation SBMA family and found that the mutant allele was unstable upon tran...

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Bibliographic Details
Published inHuman molecular genetics Vol. 1; no. 4; p. 255
Main Authors Biancalana, V, Serville, F, Pommier, J, Julien, J, Hanauer, A, Mandel, J L
Format Journal Article
LanguageEnglish
Published England 01.07.1992
Subjects
Alleles
Base Sequence
Female
Humans
Male
Muscular Atrophy, Spinal - genetics
Oligodeoxyribonucleotides - genetics
Pedigree
Polymorphism, Genetic
Receptors, Androgen - genetics
Repetitive Sequences, Nucleic Acid
X Chromosome
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Summary:Increased length of a protein-coding CAG repeat within the androgen receptor gene appears to be the only type of mutation responsible for spino-bulbal muscular atrophy (SBMA or Kennedy disease). We have analysed a large 4-generation SBMA family and found that the mutant allele was unstable upon transmission from parent to child, with a documented variation from 46 to 53 repeats and a tendency to increase in size (7 increases and a single decrease in 17 events), which appeared stronger upon transmission from a male than from a female. Our results suggest also limited somatic instability of the abnormal allele, with observable variation of up to 2-3 repeats. This indicates that the behavior of the CAG repeat is similar to that observed for small premutations in the fragile X syndrome, or small abnormal alleles in myotonic dystrophy, two diseases which are caused by expansion of an unstable trinucleotide repeat.
ISSN:0964-6906
1460-2083
DOI:10.1093/hmg/1.4.255