These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Discordance of muscular dystrophy in monozygotic female twins: evidence supporting asymmetric splitting of the inner cell mass in a manifesting carrier of Duchenne dystrophy.
    Author: Lupski JR, Garcia CA, Zoghbi HY, Hoffman EP, Fenwick RG.
    Journal: Am J Med Genet; 1991 Sep 01; 40(3):354-64. PubMed ID: 1683155.
    Abstract:
    In 1990, Richards et al. reported dramatically skewed lyonization in a set of female monozygotic twins heterozygous for Duchenne muscular dystrophy (DMD). The skewed inactivation pattern was symmetrical in opposite directions, one twin being affected with DMD, the other one being normal. Here, we report an additional set of female monozygotic twins heterozygous for a mutation at the dystrophin locus. Similarly, one shows a manifesting carrier phenotype while one is normal. However, unlike the previous report, we find a skewed X inactivation pattern only in the affected twin, while the normal twin showed a random X inactivation pattern. Our results lend considerable experimental support for the models of twinning and X inactivation recently outlined by Nance in 1990, in that these twins probably represent asymmetric splitting of the inner cell mass (ICM): The affected twin likely arose when a small proportion of the ICM split off after lyonization had occurred. In this situation, the original ICM could give rise to the normal twin with random lyonization, while the newly split cells would experience catch-up growth and lead to the affected twin. Genetic studies of this family showed that the specific dystrophin gene mutation was an exon duplication that arose sporadically in the paternally derived X chromosome.
    [Abstract] [Full Text] [Related] [New Search]