Document Detail

Discordance of muscular dystrophy in monozygotic female twins: evidence supporting asymmetric splitting of the inner cell mass in a manifesting carrier of Duchenne dystrophy.
MedLine Citation:
PMID:  1683155     Owner:  NLM     Status:  MEDLINE    
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.
J R Lupski; C A Garcia; H Y Zoghbi; E P Hoffman; R G Fenwick
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American journal of medical genetics     Volume:  40     ISSN:  0148-7299     ISO Abbreviation:  Am. J. Med. Genet.     Publication Date:  1991 Sep 
Date Detail:
Created Date:  1991-12-20     Completed Date:  1991-12-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7708900     Medline TA:  Am J Med Genet     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  354-64     Citation Subset:  IM    
Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030.
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MeSH Terms
Blotting, Southern
DNA / metabolism
Diseases in Twins / embryology,  genetics*
Dosage Compensation, Genetic
Dystrophin / genetics
Heterozygote Detection*
Multigene Family*
Muscles / pathology
Muscular Dystrophies / embryology,  genetics*,  pathology
Polymerase Chain Reaction
Polymorphism, Restriction Fragment Length
Twins, Monozygotic / genetics*
X Chromosome*
Grant Support
Reg. No./Substance:
0/Dystrophin; 9007-49-2/DNA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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