X inactivation and dystrophin studies in a t(X;12) female: Evidence for biochemical normalization in Duchenne muscular dystrophy carriers
✍ Scribed by Wenger, Sharon L. ;Steele, Mark W. ;Hoffman, Eric P. ;Barmada, Mamdouha A. ;Wessel, Henry B.
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 480 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0148-7299
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✦ Synopsis
A 4-year-old girl was identified with high creatine kinase (CK) values, and mild muscle weakness in a limb-girdle distribution. Results of dystrophin analysis of the muscle biopsy were consistent with a manifesting heterozygote for Duchenne muscular dystrophy. In peripheral lymphocytes she had a t(X;12) (p21.2;q24.33). Late DNA replication studies demonstrated inactivation of the normal X chromosome in 99.4% of cells. Dystrophin immunofluorescence showed 64% dystrophinnegative muscle fibers. Dystrophin content of muscle by immunoblot was approximately 5% of normal. The discordance between the percent of normal X inactivation and percent of dystrophin-negative cells may be explained by compensatory protection of dystrophin by rare nuclei with the normal X active in multinucleated muscle fibers with shared cytoplasm. o 1992 Wiley-Liss, Inc.
KEY WORDS Duchenne muscular dystrophy
gene, X chromosomal translocation, dystrophin analysis