In two unrelated pedigrees of Alpers ' syndrome , each affected child was found to carry a homozygous mutation in exon 17 of the POLG locus that led to a Glu873Stop mutation just upstream of the polymerase domain of the protein .
O O O O O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O O O O O O O O O O O O O O O O B-GeneOrGeneProduct O O O O O B-SequenceVariant O O O O O O O O O O O