Segregation distortion of the CTG repeats at the myotonic dystrophy locus

R. Chakraborty, D. N. Stivers, R. Deka, L. M. Yu, Mark Shriver, R. E. Ferrell

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Myotonic dystrophy (DM), an autosomal dominant neuromuscular disease, is caused by a CTG-repeat expansion, with affected individuals having ≥ 50 repeats of this trinucleotide, at the DMPK locus of human chromosome 19q13.3. Severely affected individuals die early in life; the milder form of this disease reduces reproductive ability. Alleles in the normal range of CTG repeats are not as unstable as the (CTG)(≥50) alleles. In the DM families, anticipation and parental bias of allelic expansions have been noted. However, data on mechanism of maintenance of DM in populations are conflicting. We present a maximum-likelihood model for examining segregation distortion of CTG-repeat alleles in normal families. Analyzing 726 meiotic events in 95 nuclear families from the CEPH panel pedigrees, we find evidence of preferential transmission of larger alleles (of size ≤29 repeats) from females (the probability of transmission of larger alleles is .565 ± 0.03, different from .5 at P ≃ .028). There is no evidence of segregation distortion during male meiosis. We propose a hypothesis that preferential transmission of larger CTG-repeat alleles during female meiosis can compensate for mutational contraction of repeats within the normal allelic size range, and reduced viability and fertility of affected individuals. Thus, the pool of premutant alleles at the DM locus can be maintained in populations, which can subsequently mutate to the full mutation status to give rise to DM.

Original languageEnglish (US)
Pages (from-to)109-118
Number of pages10
JournalAmerican Journal of Human Genetics
Volume59
Issue number1
StatePublished - Jun 27 1996

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Myotonic Dystrophy
Alleles
Meiosis
Trinucleotide Repeats
Neuromuscular Diseases
Aptitude
Human Chromosomes
Pedigree
Nuclear Family
Population
Fertility
Reference Values
Maintenance
Mutation

All Science Journal Classification (ASJC) codes

  • Genetics
  • Genetics(clinical)

Cite this

Chakraborty, R., Stivers, D. N., Deka, R., Yu, L. M., Shriver, M., & Ferrell, R. E. (1996). Segregation distortion of the CTG repeats at the myotonic dystrophy locus. American Journal of Human Genetics, 59(1), 109-118.
Chakraborty, R. ; Stivers, D. N. ; Deka, R. ; Yu, L. M. ; Shriver, Mark ; Ferrell, R. E. / Segregation distortion of the CTG repeats at the myotonic dystrophy locus. In: American Journal of Human Genetics. 1996 ; Vol. 59, No. 1. pp. 109-118.
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Chakraborty, R, Stivers, DN, Deka, R, Yu, LM, Shriver, M & Ferrell, RE 1996, 'Segregation distortion of the CTG repeats at the myotonic dystrophy locus', American Journal of Human Genetics, vol. 59, no. 1, pp. 109-118.

Segregation distortion of the CTG repeats at the myotonic dystrophy locus. / Chakraborty, R.; Stivers, D. N.; Deka, R.; Yu, L. M.; Shriver, Mark; Ferrell, R. E.

In: American Journal of Human Genetics, Vol. 59, No. 1, 27.06.1996, p. 109-118.

Research output: Contribution to journalArticle

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N2 - Myotonic dystrophy (DM), an autosomal dominant neuromuscular disease, is caused by a CTG-repeat expansion, with affected individuals having ≥ 50 repeats of this trinucleotide, at the DMPK locus of human chromosome 19q13.3. Severely affected individuals die early in life; the milder form of this disease reduces reproductive ability. Alleles in the normal range of CTG repeats are not as unstable as the (CTG)(≥50) alleles. In the DM families, anticipation and parental bias of allelic expansions have been noted. However, data on mechanism of maintenance of DM in populations are conflicting. We present a maximum-likelihood model for examining segregation distortion of CTG-repeat alleles in normal families. Analyzing 726 meiotic events in 95 nuclear families from the CEPH panel pedigrees, we find evidence of preferential transmission of larger alleles (of size ≤29 repeats) from females (the probability of transmission of larger alleles is .565 ± 0.03, different from .5 at P ≃ .028). There is no evidence of segregation distortion during male meiosis. We propose a hypothesis that preferential transmission of larger CTG-repeat alleles during female meiosis can compensate for mutational contraction of repeats within the normal allelic size range, and reduced viability and fertility of affected individuals. Thus, the pool of premutant alleles at the DM locus can be maintained in populations, which can subsequently mutate to the full mutation status to give rise to DM.

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Chakraborty R, Stivers DN, Deka R, Yu LM, Shriver M, Ferrell RE. Segregation distortion of the CTG repeats at the myotonic dystrophy locus. American Journal of Human Genetics. 1996 Jun 27;59(1):109-118.