RESUMO
OBJECTIVES: To report a multi-technical approach to Duchenne muscular dystrophy (DMD) mutation testing through carrier analysis, in the prenatal diagnosis of a male foetus without a known mutation segregating in the family and with inconclusive results of linkage analysis. METHODS: Haplotype analysis with the DMD region markers for assigning the carrier status of the mother and for prenatal diagnosis of foetal DNA; semiquantitative multiplex analysis of maternal and foetal DNA for the promoter and for 34 exons of the DMD gene; sequencing analysis of the maternal and foetal DNA for confirmation of the results. RESULTS: Because of an intragenic recombination of the DMD gene in foetal DNA, haplotype analysis gave inconclusive results. Semiquantitative PCR analysis displayed a pattern compatible with a heterozygous exon 60 mutation in the mother's DNA, while foetal DNA showed a normal migration pattern. Sequencing analysis confirmed the presence of a novel 7 base-pair deletion in exon 60 of the DMD gene in the mother and excluded the deletion in the foetus. CONCLUSION: Semiquantitative PCR results allowed the DMD mutation detection in the mother and the exclusion in the foetus, showing its crucial importance in prenatal diagnosis in those cases where linkage analysis is not conclusive.
Assuntos
Distrofina/genética , Doenças Fetais/diagnóstico , Distrofia Muscular de Duchenne/diagnóstico , Mutação , Diagnóstico Pré-Natal/métodos , Análise Mutacional de DNA , Éxons , Feminino , Doenças Fetais/genética , Ligação Genética , Haplótipos , Heterozigoto , Humanos , Recém-Nascido , Masculino , Distrofia Muscular de Duchenne/genética , Linhagem , Gravidez , Recombinação GenéticaRESUMO
The UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene is the causative gene for autosomal-recessive hereditary inclusion-body myopathy (h-IBM). Two sisters affected with autosomal-recessive h-IBM were shown to be compound heterozygous for two novel GNE mutations: a large deletion involving exons 1-9, and a R162C amino acid change in the epimerase domain. This is the first deletion event observed in a GNE allele and expands the molecular pathogenesis of autosomal-recessive h-IBM.
