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A MULTI-TECHNIQUE MOLECULAR ANALYSIS OF A DMD FAMILY WITH TWO INDEPENDENT MUTATIONAL EVENTS AND A MANIFESTING PREGNANT WOMAN. BIOINFORMATIC ANALYSIS OF MOLECULAR SCARS AT BREAKPOINT JUNCTIONS AND HYPOTHESIZATION OF THE UNDERLYING MOLECULAR MECHANISMS.
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  • Leonela Luce,
  • Miguel Abelleyro,
  • Micaela Carcione,
  • Chiara Mazzanti,
  • Liliana Rossetti,
  • Pamela Radic,
  • Irene Szijan,
  • Sebastián Menazzi ,
  • Liliana Francipane,
  • Julián Nevado,
  • Pablo Lapunzina,
  • Carlos De Brasi,
  • Florencia Giliberto
Leonela Luce
Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Genética, Laboratorio de Distrofinopatías.
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Miguel Abelleyro
CONICET-Academia Nacional de Medicina. Instituto de Medicina Experimental (IMEX).
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Micaela Carcione
Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Genética, Laboratorio de Distrofinopatías.
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Chiara Mazzanti
Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Genética, Laboratorio de Distrofinopatías.
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Liliana Rossetti
CONICET-Academia Nacional de Medicina. Instituto de Medicina Experimental (IMEX).
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Pamela Radic
CONICET-Academia Nacional de Medicina. Instituto de Medicina Experimental (IMEX).
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Irene Szijan
Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Genética, Laboratorio de Distrofinopatías.
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Sebastián Menazzi
Universidad de Buenos Aires. Hospital de Clínicas "José de San Martín". División de Genética.
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Liliana Francipane
Universidad de Buenos Aires. Hospital de Clínicas "José de San Martín". División de Genética.
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Julián Nevado
Instituto de Genética Médica y Molecular (INGEMM)-IdiPAZ, Hospital Universitario La Paz, Universidad Autónoma
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Pablo Lapunzina
Instituto de Genética Médica y Molecular (INGEMM)-IdiPAZ, Hospital Universitario La Paz, Universidad Autónoma
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Carlos De Brasi
CONICET-Academia Nacional de Medicina. Instituto de Medicina Experimental (IMEX).
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Florencia Giliberto
Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Genética, Laboratorio de Distrofinopatías.
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Abstract

Our work depicts a familial Duchenne muscular dystrophy case with a complex structural variant (cxSV) and a manifesting pregnant woman. Were our aims to provide molecular diagnosis and hypothesize mechanisms underlying the origin of the cxSV. We implemented a multi-technique approach including MLPA, STRs-segregation, AR-assay, SNP-array, WGS and a bioinformatic algorithm for identification of double strand breaks (DSB) stimulator motifs. We established the carrier status of the prenatal sample and explained its mother´s symptomatology by skewed X-chromosome inactivation. Furthermore, an ancestral familial ex38-43 duplication plus a de novo ex45-54 deletion was revealed in the proband, who carried the cxSV in a recombinant maternal X-chromosome. Characterization of cxSV´s breakpoints junction and its surrounding sequences allowed us to identify DSB stimulator motifs. The replication-dependent “Fork Stalling and Template Switching” mechanism was predicted to be the most likely scenario for the duplication´s origin. Whilst, the de novo deletion could arise from a germline event of inter-chromosome non-allelic recombination involving the “Non-Homologous End Joining” mechanism. The multi-technique strategy enabled precise diagnosis, accurate genetic assessment and widen the understanding of the molecular mechanisms involved in SVs’ generation. Finally, the further comprehension of the occurrence of DMD variants, favors the development of new gene therapy strategies.