title: Xp21/A translocation: a rarely considered genetic cause for manifesting carriers of duchenne muscular dystrophy.
abstract: Clinically manifesting carriers of Duchenne muscular dystrophy (DMD) are rare among the pediatric population. A standardized diagnostic procedure in supposed DMD carriers entails performing a Multiplex Ligation-dependent Probe Amplification analysis of the DMD gene first, then taking a muscle biopsy to confirm reduced dystrophin levels and/or finally a complete sequencing of the DMD gene. We describe a girl with high-elevated creatine kinase, myalgia, and cardiomyopathy. Muscle biopsy showed a dystrophic pattern and nearly absent expression of dystrophin. Diagnosis could not be confirmed by molecular genetic procedures. Because of a mild mental retardation, a chromosome analysis and molecular karyotyping were performed, revealing a balanced translocation t(X;4)(p21;q31).arr(1-22,X)x2 dn with breakpoint on the X-chromosome within an intron of the DMD gene. The inactivation of the nonderivative X-chromosome was found to be in a nonrandom pattern, resulting in a functionally balanced karyotype and thus leading to a manifesting DMD carrier in this case. Chromosome analysis should be recommended in cases of genetically unsolved DMD carriers as a part of the standard genetic procedures.
authors.affiliation: Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Essen, Essen, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Trippe
authors.affiliation: Department of Human Genetics, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wieczorek
authors.affiliation: Department of Human Genetics, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Judith
authors.initials: J
authors.lastname: Kötting
authors.affiliation: Centre of Human Genetics, University of Würzburg, Würzburg, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Kress
authors.affiliation: Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Essen, Essen, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schara
mesh_terms: D002675:Child, Preschool; D041321:Chromosomes, Human, X / Q000235:genetics*; D005260:Female; D006801:Humans; D007621:Karyotyping; D008279:Magnetic Resonance Imaging; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis / Q000235:genetics*; D014178:Translocation, Genetic / Q000235:genetics*