DMD GENE SMALL MUTATION SCREENING BY WHOLE EXOME SEQUENCING

LUCE,LEONELA NATALIA; ;PARMA, DIANA; ; PENAS STEINHARDT,ALBERTO; ; SZIJAN, IRENE; GILIBERTO, FLORENCIA

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Exposici�n; JORNADA DE DIVULGACIÓN DE LAS ACTIVIDADES DEL DEPARTAMENTO DE MICROBIOLOGÍA.INMUNOLOGÍA, BIOTECNOLOGÍA Y GENÉTICA. FACULTAD DE FARMACIA Y BIOQUÍMICA. UNIVERSIDAD DE BUENOS AIRES.; 2018

FFYB UBA

DMD GENE SMALL MUTATION SCREENING BY WHOLE EXOME SEQUENCINGLuce, Leonela1,2; Parma, Diana2; Penas, Alberto3,4; Szijan, Irene2 and Giliberto, Florencia1,2.(1) Universidad de Buenos Aires. CONICET. Instituto de Inmunología, Genética y Metabolismo (INIGEM). Buenos Aires, Argentina.(2) Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Genética. Buenos Aires, Argentina.(3) Universidad de Buenos Aires. CONICET. Instituto de Estudios de la Inmunidad Humoral (IDEHU). Buenos Aires, Argentina.(4) Universidad Nacional de Lujan. Departamento de Ciencias Básicas. Luján, Buenos Aires, Argentina,Duchenne Muscular Dystrophy (DMD) and Becker Muscular Dystrophy (BMD) are X-linked genetic diseases caused by mutations in the DMD gene. DMD is a severe dystrophy that affects 1:3500 born males, whereas BMD is less severe and affects 1:18000. Molecular alterations responsible for DMD/DMB are gross deletions and duplications in 70% of cases and small mutations in the remaining 30%. While large rearrangements are identified by MLPA, point mutations are detected by gene sequencing. This study aimed to detect small mutations in the DMD gene by Whole Exome Sequencing (WES) in 9 boys with presumptive clinical diagnosis of DMD/DMB and a woman obligate carrier. WES was performed by Macrogen service and the pathogenicity of the identified variants was determined according to: its presence in a DMD mutation database; its absence in results of sequence consortiums such as 1000genomes and Hapmap; and online predictive softwares (polyphen, SIFT and Mutationtaster). We have found in the affected boys a range between 7-18 sequence variants in the DMD gene, when in the only woman studied we detected 33. We were able to identify the disease causing mutations with 100% certainty in 9 cases which consisted in 5 nonsense mutations, 1 frameshift deletion, 2 frameshift duplications and 1 altering a donor consensus splicing site. In 2 of these cases, we also found a missense mutation predicted to have a negative impact on the dystrophin protein. In the remaining case, we have identified an in-frame deletion determined as a Variant of Uncertain Significance (VUS). Finally, we can conclude that this screening methodology was able to detect small mutations in the DMD gene in 9/10 individuals, allowing confirmation of the diagnosis in the boys. Further studies should be performed in order to establish the pathogenicity of the VUS. The importance of this work relies on the fact that is the first one applying WES for DMD/DMB molecular diagnosis in Argentina. Palabras Claves: Duchenne Muscular Dystrophy; Becker Muscular Dystrophy; Point mutation screening; Whole Exome Sequencing.